Windows is not only for gaming. You could well use this as a cheap desktop PC-replacement in perhaps schools. MS Office, web browsing and such for the less linux-prone users. If you aren't a tech-savy person who just uses the computer for occasional web browsing and doing some administration, this could be a cheap solution. A lot of people are accustomed to Microsoft products and some simply don't want to change.

Plus, I think this is a great marketing move for Microsoft. They want to/have to maintain a foothold on multiple platforms. Who knows, maybe we don't know why someone wanted to run Windows on a RPi2, but that person could very well have a good reason. Don't judge before you don't know the real reasons.