Theres a lot of speculation in your post. I to was skeptical about why the guards let him out with the video camera but the guards wouldnt think aliens were filmed so could easily have just let them go without going to the big bosses. Also no guarantee you get killed for having info because area 51 would know he had no real evidence and it was all just talk.

With the alien body i believe he said he didnt want to talk about it cause he wasn't certain and he only saw it for a fraction of a second so never used that as proof, it was the annoying guy who made the documentary who brought it up.

You say the government will kill him if he was right but you dont think they would erase his college transcripts to make him look like a liar???

Your story of him trying to get a job at los alamos to get recruited to s4 also makes no sense. Why would he try to get a job at los alamos in the off chance he meets someone who works at s4 and could get him an interview there later.

For the record i'm hesitant to believe him because he couldnt tell you much about mit, you would think he could name off a bunch of teachers right away if he actually went there but i'm pretty sure in the past he was on record naming a teacher that never existed. However it does seem safe to say he actually did work at s4 for a fairly long period of time since he knew when the "spaceships" would be flying around.