I work for MS, right now we're working on win10. Some of the UI is written in html/js now, so I'm not surprised by this at all. I'm guessing we'll see some native node.js apps on windows in the future.
I think what the OP meant was that it is interesting that MS forked Node, and not the io.js project that's more advanced than Node.
IMO it's not too surprising - it's relatively simple to fast forward to io.js from where it is now, wheras reverse engineering it backwards to Node compatibility would be mayhem.
