But there's so much more here. He got arrested and put in juvenile detention. He was interrogated by the police without his parents being informed.

There's no excuse for this. The police involved should lose their jobs and spend some time in jail themselves. Not a lot, but perhaps a couple of days will get some of their colleagues to look up "probable cause" and "civil rights." The principal should lose his job as well, since he is clearly not mentally competent to supervise children.