He could have been at risk for hurting himself or other kids
I haven’t personally dealt with autism but I have seen a kid get absolutely out of control and the poor mother in tears apologizing to everyone saying her kid had autism.
I have a 25 year old stepson with autism who lives with us. We sleep with the master bed door locked and I keep a pair of handcuffs in the drawer next to the bed.
He has had several violent meltdowns over the years and can be quite dangerous when highly agitated. Thankfully it only happens maybe once a year and we have learned how to spot when a meltdown is coming on and how to medicate him in advance.