Even if he had violated the dress code, which he apparently hadn't, how does his refusal to remove his shirt become a matter for the police? Are violations of a school's dress code now part of criminal law? If so, what specific statute?
I believe those are rhetorical questions, right? This is the reason why is this so asinine. Unfortunately, we live in an age when people call 911 when they get the wrong order going though a drive thru window. The herd needs to be culled.