Being an "Aspie" myself,I agree with *Nelliemoser" about your son in law probably having a mental health issue that causes his behaviour.Does your daughter happily live with his routines and idiosyncrasies?Has she ever complained about them or said that she finds it difficult to cope with?She has probably just got used to his ways and accepts them.I would definitely ask her about this if I were you.
His behaviour is probably part of his character make-up and although I understand your irritation,I don't think it is worth rocking the family boat over.I would think twice about moving near to them for the time being though,especially as you have other reasons to stay put.
Adult offspring harbouring resentments

, but it cleared the air and things have settled into a jokey ... may I ... routine when he is here