Earlier quoted context omitted.
Even more surprised that no one seems to recall that they did exactly this back in the day. There was a version of the NT4 kernel that could run Unix programs. "Great, the program selection of Unix with the stability of windows!" people sneered, but still there was a market for it.
But that was a whac-a-mole, probably for getting boxes checked for whatever it is that audit departments did before sarbanes oxley. That they've gone with linux here shows that their focus is mainstream developers. Consider - it their main focus here had been EEE then BSD would have been a far better starting point. The GPL is far more restrictive than the BSD license. The one major area where linux wins over BSD is…
What Microsoft has created is binary translation for Linux system calls, like Wine but allowing Linux to run on Windows instead. FreeBSD, among many other OSs, has done something similar for a long time, precisely because Linux is the most popular Unix-like OS. In addition, Microsoft doesn't care about the drivers -- everyone still writes drivers for Windows.