To me, it seems like the ruling only takes away powers from teachers/administration and has no effect on legal system. Meaning that if it had been sadistic tactics towards young boys, the law can't do anything beyond what already exists (e.g. harassment, stalking, libel) no matter how the case would have gone.

I'm all for taking powers away from school administrations. Teachers and admins are group ripe with hate, favoritism, self-importance, and a sense they have to do a fake justice to everything. If a young boy had been the victim of sadistic girls, I'd expect the school to turn it around on the boy myself. I'd prefer the law be there that the school can't do shit to any parties for outside of school things. It may not stop the boys from harassment, but it will stop the school from being a party to it, at least legally.

I read Thomas' dissent as well, it's mostly having to do with precedent. It's not a horrible argument he puts together, if you believe in the precedent that schools are the kids parents when they are there. "In loco parentis" is the term he uses.