First, it totally stinks that your kid got put in this situation, and I feel very bad for him.
A couple thoughts…
- There's probably a reason there was a space available in that suite. The other guy probably said the heck with this situation and moved out.
- When I didn't come back after my freshman year, my two suitemates were terrible to every person who tried to move into my spot-nobody lasted more than a week because they wanted the space to themselves. That could also be what's going on.
If it were my kid I’d try to get him moved, and if he can’t move, at least externalize the situation, start cleaning out and claiming shelves in the fridge and making it livable for himself, and to heck with the rest of the guys. There’s no upside to being nice or socializing with them, so do what he has to do to make it decent until he CAN get out.