Phil has spent a lot of marketing money crafting a public image that is near unimpeachable. Its been his saving grace during his entire tenure at Microsoft. Its an organization that rewards yes men above all. You can stay on as long as you want, fail upwards, as long as you tell them what they wanna hear.
As long as your perception isn't dropping below a certain level, you'll stay there. But once it does, like a few names I won't name but you know exactly who I am talking about, and I am referring to notable studio leadership as well as publishing leadership within Microsoft. And even in those situations, they let you leave with a public-facing cover story so you can go and get a nice E-suite level job elsewhere.