"very unlikely broke any law trying to to tell this poor father to do anything.. but even if they did, this is not the issue"
IIRC, the principal did not call the father. One of the girl's teachers did. The principal asked the father not to call the police that day, but, rather, the next, saying something to the effect of he would be pleased with the outcome or some such. Having followed the story, it seems one of the LEOs for the HS was off that day. It could also be a delaying tactic to simply allow the heat of the moment to evaporate and the evidence to disappear.
I do have a question: are the girl and her attackers of the same race? Does anyone know?
Probably. The school is apparently about 85% black, according to the thread linked above.