I'll tell you a little story about something similar that happened to my son.
it was around the time of the Haiti earthquake.
His friend set up on facebook, I think, a Haiti Haters message board, basically the point being that why are we giving money to Haiti when we have very poor people here in America. Yes it was stupid, but not necessarily vindictive or insulting. Just a teenager questioning the world. and yes Haiti Haters is a horrible name. But the discussion was not about hating Haitians, just about priorities of money spending.
now my son participated but didn't really post more along the lines of deleting messages from the chat that were too negative.
Again, a stupid thing to do, all agreed.
he was going to an exclusive catholic private school at the time and one of the kids reported the facebook chat to the school. The school was not part of the facebook conversation, nor was it's name anywhere near it.
My son is a great kid, NEVER any trouble, responsible, respectful, always treats people well, lots of friends, good grades, participated in lots of school activities.
The school suspended him for 2 weeks (in school, so it was basically sit in a classroom for 7 hours a day doing nothing), kicked him out of the National Honor Society, didn't let him go on the senior trip that he had paid for (around $1K) that the school didn't refund, didn't allow him at any school function, didn't allow him to attend prom. Did EVERYTHING but expel him and the reason they didn't do that is cause they knew that if they did they would be sued. They let him attend graduation, but again, only to be able to hold that over his head to keep us from raising a stink, as they threatened him with taking that away.
Now I accept that he made a mistake, but there was NO proportionality in the response. The school was SOLELY interested in how THEY looked. They said that to him. His punishment had NOTHING to do with teaching him a lesson about his actions. And again, he realized once it was over how stupid it was, (the whole online episode lasted a couple of hours). He was just too young to understand the true poverty of Haiti and the devastation of the earthquake. AND he was in his own way questioning and exploring morality. The poor people he was talking about live in a neighboring city (Camden NJ) that he had experienced through community service.
So I have personal experience with this type of injustice.
Funny thing, was my ex wife wouldn't tell me about what was going on (we were separated at the time) at the time (i.e. meeting with the school) cause she knew I would have gone off on the school. We were at the point where we were worried the school would contact the College he got into to get him kicked out of there.
Karma works though, cause the school is having a difficult time finding students, may close in a couple of years. They are down like 25% on number of students since my son was there. AND I have 3 other kids who could have gone there. So I guess we "won" in the end.