I'm confused by much of what the OP decribes.
As far as sensitivity to touch, for those that are, it's much like a feeling of torture to them. A sensory overload. It can feel painful or like burning.
I probably would not have left him alone to be responsible for two young children.
I also don't see where touch has anything to do with rescuing a younger child from a situation. Do you mean he does not like to be touched and does not like to touch others as well?
If that's the case, he can't turn it on and off because the situation demands it If things were that easy, chances are AS wouldn't be much of an issue for anyone Not simply a choice here.
_________________
Bunni
That which doesn't kill me, makes me stronger, and really pisses me off.