He edited the Swan Orientation Film as "insurance" in case he was killed or replaced before his plan came to fruition. He wanted his and Kelvin's replacements to stop pushing the button, thereby triggering a system failure that would give away the location of the Island.
He removed all information about the nature of the Incident and the consequences of a system failure because he wanted the viewer to suspect that all the information in the film is meaningless and that nothing will happen if the button is not pushed.
He left the reference to B.F. Skinner in the film because he wanted the viewer to conclude that the Swan Station is nothing but a giant Skinner box.
He smuggled the deleted footage out in the hollowed-out Bible for the same reason that he and Kelvin hid the map on the blast door - because he didn't want the people running the experiment to know what he was up to.
He edited the video so that other people stuck in the Swan would discover that they were out of time by contacting the outside world.
He edited the Swan film sometime after the purge. The film was edited to remove the section about 'Using the computer for contacting the outside world" and "Could lead to another incident." He edited the film after the purge because he wanted to make sure any following replacements would not use the computer for contacting anyone outside (most likely other DHARMA stations on the Island as Michael did) - this could lead to another incident because the original swan site incident was caused by Jack, Kate, Sawyer, Juliet and others with the nuclear bomb in 1977. He believed them to be 'Hostiles' - and therefore if the new recruits contacted the 'hostiles' they could jeopardize the Swan stations purpose.
He edited the Swan film to remove any references to The Incident to ensure that it actually happened. If he finally understood that the island made time travel possible, then perhaps he figured out that one day the people who caused the incident would be in Swan Station watching the orientation video, and he didn't want them to know too much about the incident as it might cause them to NOT do what they were supposed to do.
He edited the Swan film to use as a secret message for a potential Dharma rescue team. He took a section from the film and placed it in The Arrow, along with a radio and his own glass eye. The glass eye was to prove his own identity, the radio was for the finder to communicate with him, and the section of film was intended to show legitimate Dharma personnel what Radzinsky's location was, without tipping off any Hostiles that might find it. Dharma would recognize the Swan film and know the location, but the Hostiles would not.
Radzinsky survives the Purge because he is fiercely protective of the Swan, and refuses to leave it. We see this when he's designing it - he would rather violate the truce and kill Sayid than let any information about the station get out. His creation of the model and blueprints suggest that he's designed the entire station, and that it's his pet project. He may be more loyal to the station than to DHARMA itself, so when the Purge occurs he never leaves his station to fight back, like most other DHARMA members would.
It has been mentioned that the Swan station was under design since '71 (and likely completed in '79).
This could also been a reason for his suicide, as he might be suffering from survivors guilt from the purge.
If the Swan is operational in 1980 and the Purge is not until 1992, it seems unlikely that Radzinsky has been stationed there for 12 years as one of the two operators to press the button. It would seem there were no experiments there after the Incident, so his pet project was a failure.
There is proof that he was stationed there and being monitored at the Pearl - Kate saw a notebook where someone with the initials of S.R. was observed.
There is no proof that S.R. was Stuart Radzinsky, though it could have been. The nature of The Swan Orientation Film indicates that the two people assigned to The Swan were rotated every 540 days. If Radzinsky were a permanent resident, there would be no need to have an orientation film to tell new personnel what their jobs are.
In a previous time loop Radzinsky was a test subject for the Swan and was not a Dharma scientist. He was sent back in time in Dharma experiments that had been carried out in the Swan. He contacted the outside world by using the computer and discovered that he was out of time and had been lied to about there being a disease on the island. He then used the time travel to his advantage and went back in time and altered the future. He studied science and became a Dharma scientist. He caused the Incident on purpose with future knowledge. This was similar to what Desmond experienced and how he wanted to change his life with Penny but he was warned against it.
Kelvin shot Radzinsky in the head when Radzinsky told Kelvin that he wanted to leave, much like Desmond later kills Kelvin when he finds out that he wants to leave. In both cases, the cause of death is a head wound.
He was murdered by Kelvin, perhaps because Radzinsky had gotten on his last nerve. As evidenced in Live Together, Die Alone, Part 1 written in one of the logbooks at the capsule dump, "0400: S.R. moved the ping pong table again.", it seemed as though Radzinsky had constantly been the bane of Kelvin's existence and likely acted in a similar matter as he did on the surface, being extremely stubborn and "my way or the highway", and Kelvin, having had enough of Radzinsky, shot him in the head with a shotgun, sending his brain or some part of him upwards to create the ceiling stain in the Swan.
One of the skeletons in the polar bear cave was Radzinsky. The top part of the skull was missing, and Kelvin said that Radzinsky used a shotgun to kill himself.
When Desmond asked Kelvin where he buried Radzinsky, he said he only had 108 minutes to do it. He may have not buried him well and a polar bear dug him up. Or Kelvin just threw him into the bear cave.
Although one of the skeletons has a Pearl logo on the shirt, this could just mean that Radzinsky was originally an operative at the Pearl station who was forced to move to the Swan when he saw something (e.g., the former button-pushers dying) on the Pearl's monitors.
Radzinsky became a close friend of Kelvin's and Kelvin was telling the truth about his death. Being close friends is why he didn't want to talk about Radzinsky's death.
After a long time without replacements (due to the purge) Radzinsky began to explore the island, creating the blast door map while Kelvin pushed the button. After much exploration he realized the rest of DHARMA were gone. Feeling like he'd been left behind with no replacements coming he became depressed and shot himself.
As seen in "The Incident, Part 1", Radzinsky is a major cause of the Incident. As a result, he will feel responsible, even guilty. He will not be forced to push the button, but instead will volunteer as his penance for the pain/death he caused by insisting that he was right. Ultimately, though, the guilt becomes too much to bear and he kills himself in the Swan station.
Radzinsky will be isolated from the DHARMA Initiative, as punishment for his mutiny and because he is largely to blame for the Incident. His curiosity and ambition, which drives him to build the Swan and learn about the island, will also drive him to draw the map (in secret), and continue his own research. Inman will come around the time of the Purge (perhaps after). They will find out about the Purge, and Radzinsky will go crazy and (being such a violent person) kill himself.
Radzinsky committed quantum suicide as in the speculation from the a variation of the Schrödinger's cat thought experiment regarding "quantum suicide and immortality ". It would mean that Radzinsky and Dharma were experimenting with ideas that we know only as theortical quantum physics. They were putting these theories into practice. He and Dharma would have created time travel so that many possible timelines could exist almost simultaneously by creating a time loop where time would be repeated over and over and slight changes would be made in each loop. This enabled him to access a myriad of alternate realities and maybe even other people's consciousnesses. This would make him Jacob's nemesis having taken on another person's form.
There is a lot of evidence to support the idea of a time travel loop. The idea that we have not always been watching one version of the timeline but a combination of various alternatives. The timeline is being changed and could possibly be the war that Widmore mentioned - a war over controlling the timeline using time travel. Many of these pieces of evidence have been excused as continuity errors but they could also mean collectively that there have been many alternative timelines shown to us that look like just one continuous timeline. Claire's Mum's seemingly miraculous recovery; Desmond's visions of other possible versions of events (Claire being on the helicopter for example); these are just 2 of many discrepancies. Then there is also the fact that the Others would leave the island for some unknown reason, eg Widmore.
Another possible timeline change, Charlie claimed he did not know how to swim at the beginning of season 1. Season 3, Charlie swam into the Looking Glass, an under water Dharma station. The distance of that under water swim could only be made by a well experienced swimmer.
He got frustrated at being unable to paint the map on the Blast-door from memory, so he used a shotgun to paint his memories on the ceiling. So to speak.
Kelvin told him about his encounter with Sayid during the Gulf War. This deeply disturbed Radzinsky, who remembered Sayid as the 'Hostile' who saw the plans for the Swan back in 1977, and drives him to suicide.
Radzinsky was infected with the Sickness and in the resulting mental anguish killed himself with the shotgun.
In his explorations of the DHARMA stations, Radzinsky discovers the Pearl or the capsule dump and realises that his work was merely a psychological experiment on himself. He believes that his work has been for nothing and in despair, he commits suicide.
Kelvin thought that Radzinsky was exposed to the sickness, so he he killed him.
The Swan station and the Blast door map
An impostor drew the Blast door map. We saw in Namaste that Radzinsky was stationed in the Flame, which seemed to be a place from which one could monitor the whole Island. He says that if there were a plane he would know about it. From this we can infer that he has a reasonably good idea of the layout of the Island, or at least the DI's installations. However, if you read the Blast Door Map, it seems to be written by someone who is trying to figure out and record where everything is. A map written by the Radzinsky we saw in Namaste would have been a lot less uncertain.
The real Radzinsky died in the purge. A defected Other took his identity. On the blast door map there a phrases written in Latin. Latin is a language all Others have to learn, according to Juliet as it is the 'language of the enlightened.'
Kelvin said that Radzinsky started the map and then killed himself. The uncertain parts of the map were written by Kelvin, who was picking up where Radzinsky left off. It seems like he doesn't know much about the island and could only fill in uncertain details. Details like "possible burial site of Magnus Hanso" were probably written in by Radzinsky and not Kelvin.
Radzinsky becomes trapped in the Swan following the Purge. The Blast door map is his attempt at recording his (apparently photographic) memory of the layout of the Island, where the stations are, etc. It's only natural that he would not remember every single one.
Radzinsky became a member of the Swan station following the Incident, as he was one of the developers of that station. He wanted to stay there as a guarantee that the button would always be pushed. Also, the map had many conjectures about DHARMA and its stations that dated from the mid 80's.
Radzinsky will be affected due to the Incident and this will damage/erase/"swiss-cheese" his memories. His creating the blast door map from memories or exploring was his mind's way of trying to reclaim what he lost. His suicide was a result of his failure to do this.
He painted the map to review his memories of his time on the island while he has been in the swan. In 1977 he might have been in his mid-forties meaning in the late ninties he wouldve been in his sixties and he was going senile from old age, hence he painted his memories on the blast door. It could explain why he painted "Alleged location of the Flame" since he wasnt 100 percent sure of his memory.
Radzinsky will be relegated to the Swan as a result of his causing the Incident by continuing to drill into the pocket of electromagnetism. Being so close to the electromagnetism will cause his memory to fluctuate like Faraday's, causing the discrepancies in the blast door map.