I think their are only three possibilities on how he was able to commit Suicide while on 24/7 Suicide watch. The first is that the Guard responsible for monitoring him was paid off. The second is that the guard responsible for monitoring either fell asleep or left his station for awhile. The first possibility seems to be the most likely as even if the Guard fell asleep or left his Station, how would Epstein know that precisely when it occurred. The third possibility was that he was murdered in a joint conspiracy involving the Suicide Watch Guards and one or more inmates. I somewhat doubt the third possibility.
You forgot #4 - he’s still alive and sipping a margarita on a remote island under an assumed name.
He wasn’t going to talk. If he was, he would have already started and he would have been in protective custody somewhere. He offed himself because he couldn’t stand the thought of being beat up every day in prison for the rest of his life. Doesn’t explain the breakdown of the suicide watch part, but at any rate, Epstein was the key player here and wasn’t going to get any benefit by outing anyone. Thus, him dying means little to nothing if anyone else was involved. There are still victims that can testify.
The Clintons no longer have the ability to arrange this sort of thing anyway. At least not and get away with it. In the very unlikely scenario that the suicide watch guard was bribed, the FBI will find out and get the source. LEO types are usually the first ones to squeal.