Essentially, the ruling says it's not a violation of a students free speech rights keep him from wearing an American Flag tee if the intent is to keep another student from kicking his ass. Of course the problem here is the Hispanic students see themselves as Mexicans and not Americans; how else do you explain the "their flag, our flag" comment contained in the court's ruling?
The wearing of an American Flag tee shouldn't be a provocative action anywhere in America. Yes, free speech rights are limited in schools, but not eliminated. Imagine the precedent this sets; call it the "intimidation clause." If someone doesn't like what you have to say, even on a tee shirt, you shouldn't say it.
How does that NOT violate First Amendment rights?
Photo Credit: By HARRIS.news (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons