I realize they have a lot of kids to handle and it's hard to listen to everyone's story, but I think he was treated unfairly and I don't like the idea that "life is just unfair and he should just accept it". Should I get involved?
There are many more worthy "battles" than this one to expend your or your son's energy on; if this situation repeats itself, I think your son should have a plan in place, knowing whom to appeal to and how to appeal so he will have the best chance of being heard. Additionally, a 12-year-old boy risks far worse problems from peers if his "mommy fights his battles" than if he rolls with the punches.