Windows doesn't even make up 1/5 of their income, and in contrast a bit over half of their income is Office and Cloud*
The real money is in enterprise IT and cloud services. The average consumer doesn't keep their prebuilt computer long enough to buy another version of the OS. They don't need to keep a niche within a minority (privacy-oriented customers who would buy an OS) happy with Windows to continue drowning in revenue.
It seems like he has done a fantastic job, if the goal was to decouple their fortune from Windows.
*Based on googling and a lazy reluctance to dig through their earnings calls