“Hostile learning environment” won’t cut it as long as the “hostility” is created by mere speech. Read Professor Eugene Volokh’s article on this at the Volokh Conspiracy blog (Washington Post). It’s a public university so the First Amendment applies.
I read it and, sure, there's a case to be made. I just don't see his family pursuing this. The kid has apologized profusely. His parents are deeply embarrassed. Their earning potential is being affected as well. If they try to make a case out of this, everyone is going to get dragged through the mud.
I don't see it happening.