This is why we don't see more open source developers developers migrating to develop on Windows. They are curious but then they hear how open source is a terrible abomination according to Microsoft. (Admittedly, not the exactly the same, in one case rms is attacking your new choice, and in the other Microsoft is attacking your old choice, but it doesn't make either side attractive to the other).

I don't think we've really heard much about Microsoft needing more developers though. Certainly not in the sense that open source needs more developers.