“It would not be hard to argue the parents “created a situation where the risk of great bodily harm or death was very high”.”
Except for the fact that the shooting occured right after that meeting. If it was so urgent, the school should have expelled him immediately and then the parents would have to take him home.
True, the school should have expelled him, or at least searched his backpack, even though the school did not know he had just been given a handgun like the one in his disturbed drawing.
That still does not excuse the parents who knew he had been gifted that handgun days ago, and had just been shown proof of how disturbed he was.