Damned if you do, Damned if you don't

The ACLU is suing a school in Florida for not allowing students to wear T-shirts that say: Islam is of the Devil. They think this is a first amendment issue.

In my classroom if someone put down another student verbally (calling them stupid, using profanity, sexist, racist terms, etc) I would be fired if I didn't respond. It's called sexual harrassment or a hostile learning environment. The school would be sued for allowing this.
Speech which denigrates, demeans or offends other students is not protected under freedom of speech in the classroom or at the school and it's functions.
The number one right of students at a school is the right to learn, this endangers that right. The number two right of students is the right to safety. These T-shirts legally constitute "fighting words" or saying something so offensive that it can cause a fight. Again if a school allowed this and a fight did break out at the school or against another school at a game and students were harmed the school would be sued.
The school does the legally required precaution of not allowing a hostile learning environment and gets sued for not allowing freedom of speech.
Damned if you do and damned if you don't.
What the ACLU (and I support the ACLU on many of its issues) doesn't figure into this lawsuit is that the money spent on these lawsuits amounts to grand theft from the coffers of the taxpayers who pay to educate their children not enrich lawyers.