Earlier quoted context omitted.
Microsoft cares because if Mac laptops have twice the battery life of windows laptops, nobody will blame Intel
It still doesn't make sense for MS to push ARM that way - Apple isn't offering its ARM processors to 3rd parties. The best non-Apple processors are obviously x86 right now.
I'm deeply fascinated by these questions. I'd love it if someone in the chip design industry who is knowledgeable about the situation would comment.