Forget the school. They aren’t a police force. The students weren’t the ones wanting to evict him. In the school’s eyes he was a guest of the housemates. Parents didn’t get a say. Participants were legal adults.
I’ve been interested in cults since college. A girl I knew joined a “church” and within a few short weeks cut off contact with everyone. Her parents were frantic and contacted everyone possible to get hold of her to no avail. Its not a matter of “just going in and grabbing your kid”.