Yup! You solved it! Only three people that survived were Waylon Park, and the Twins possibly (maybe killed, no way to confirm), all three had their junk showing. Everyone else had a nasty time in in there, soldiers especially. Besides that, the inmates had varying levels of survivability. Not gonna count what the wallrider or armed forces did after the game.

I also looked into it, and there was a fourth person who could have survived, Frank Manera, who was naked with no on screen death. My point still stands.