I have read a few times that Michigan does NOT have a law that requires firearms to be locked/secured. Maybe after this Michigan will consider changing their state law to require gun owners to be more responsible because it is obvious (at least these parents/gun owners) that it is not common practice just to be safe.
Also, I am curious if the drawing he made was being interpreted as him asking for help and that he was at risk of suicide, not mass shooting. That would make sense then for the school to ask parents to have him in counselling within 48 hours and thinking he would at least be safe (from hurting himself) if he was in class rather than (possibly) home alone?