I think the culture of that suite was already established when he moved in mid semester, so there is little he is going to change either with the mess or the gaming. He should not take it personally as the other 3 are not interacting with each other either - they seem obsessed with the gaming. I would suggest that he look to make connections elsewhere and I am sure that he will. Gamers are a breed of their own, not necessarily negative but their priorities are different than say a more athletic or theater oriented student.
It does not sound like he would be compatible with these guys anyway, so he should just stick it out for the semester and use this semester to cement relationships that will lead to new housing for next Fall. I think the best roommate situation is where you get along with the others but they are not your core social circle.