It depends on his age. Yes, the school has the right to suspend
  him - it is school polity. HOWEVER, I think it would be
  beneficial to bring him back in and use it to discuss civil
  liberties in social studies classes and use it as a way to teach
  civil disobedience. I'm sure it will be used as an example case
  in other high schools and colleges if the story goes nationwide.
  The danger of course: Will this encourage further civil
  disobedience and is the school prepared for it? Is it possible
  to put the genie back in the bottle? "