Enterprise, of course. They probably buy more PCs than the rest of the market combined.

Even for personal use, I'd imagine the amount of people dual booting Windows and something else are a very tiny minority.

Saying "Windows PC" is a pretty reasonable way to distinguish between "made by Apple" and "made by someone else" because the market of PCs that aren't made by Apple and don't come with Windows is really, really tiny.

To be honest, this seems like a strange hill to take such an aggressive stance upon.