There was a Supreme Court decision called the Tinker decision in which some school students during the Vietnam War wore some black armbands in protest. The school said they couldn’t do so, even though they allowed various other sorts of symbols to be worn by students, including certain German army symbols. The parents of the kids sued and won and the Supreme Court said that students had certain free speech rights as long as their speech was not materially disruptive to the learning environment.
The Court held that for school officials to justify censoring speech, they “must be able to show that [their] action was caused by something more than a mere desire to avoid the discomfort and unpleasantness that always accompany an unpopular viewpoint,” allowing schools to forbid conduct that would “materially and substantially interfere with the requirements of appropriate discipline in the operation of the school.” The Court found that the actions of the Tinkers in wearing armbands did not cause disruption and held that their activity represented constitutionally protected symbolic speech.
If nothing else, the shutting down of the Mount Si Hot or Not contest should help cause some people to learn about the Tinker decision.