If I'm not mistaken, the view is,

a) don't want to provide nice tools to windows users because then they'll no longer have the need to switch to a libre system

b) do want to provide nice tools to windows users because then they'll get a taste of how liberating freedom is

obviously there is a balance there, and I think GNU/NT might be a bit too far into entrenching-the-user for his tastes, though I can't speak for him obviously.

It seems there is no political note on his site for the announcement of ubuntu-on-windows.

Richard calls it "GNU/kWindows" (like GNU/kFreeBSD); I wrote an article with his input a while back:

https://mikegerwitz.com/2016/04/GNU-kWindows

It's not running the Linux kernel, but it's implementing Linux kernel interfaces. Microsoft may ship a lot of GNU software now but presumably the same interfaces could be used to run alternatives like busybox and uclibc. This keeps the naming debates interesting, I suppose.