I think the man is seriously amazing, and has probably just lost the plot with us ordinary beings, who have spend the last 50 years trying to catch up with his vision.
I'm not sure how Apple's infrastructure works but I can't see Bill just walking away from MS if it was to start going down a slippery path. If it did I can see him intervene.
Bill has MS through and thought and it literally is his baby. I know if I built up a company of that magnitude I would want to leave knowing what direction it is going and having the best people in who I trust to keep it on track.