Hm. Well, many kids on the spectrum to self stimulate. What you do is tell him no no when he does it on our lap. I don't think he sees you as a sexual object. He's 5. kissing mommy is comforting as is being kissed. My sons are both very affectionate and my older son who has sensory integration disorder likes firm hugs which is deep pressure for his nervous system. So, I'd view kissing as loving and not sexual. Don't put adult thoughts on a child. If you feel the kissing is over the top, set limits. Kiss but not on command and not constantly. good luck