Are ewe saying that the first amendment does not protect undesirable speech?
Nope. I'm saying that it doesn't protect speech that would result in harm to others. That determination is made by the schools admin.
Nice try though.
Why would chanting USA cause harm?
You will have to ask the school admin about that if you want a definite answer. They made the determination.
However, I will hazard a guess.
Bratty kids from a predominantly white school face a team with many Hispanic kids on the team. They decide that chanting USA! from the stands would be sufficiently insulting to the brown kids, who will accurately take the chant as an insult...since they are, in fact, also Americans.
In other words, they were using the mask of patriotism to denigrate the brown kids.
If you were one of the brown AMERICAN kids in that picture, us probably be upset. No?