This is a clear threat to liberties. Allowing a school to disallow wearing clothing donning the American flag because they fear race-based violence is downright cowardly, and a slippery slope that people should be really concerned about.
A California school decided to ban such clothing on Cinco de Mayo for they feared fights to break out. The Ninth Circuit today ruled that such was acceptable.
Heckler's veto has prevailed, and the thugs have won. Damn the First Amendment, because the school is too afraid to stand up to thuggery. So instead of affirming the First Amendment (this is the one I really care about more than all the others), they basically said: If you dislike what someone is saying, just threaten violence.