So this doesn't negate the license. Microsoft cannot just roll the code into windows for example, closed source and proprietary. They have to abide by the license, regardless what their ToS says.

Here's a fun way to see it, suppose someone writes code licensed GPL. I take it, fork it, modify a line in it or not, and also license it GPL because I have to by law. I put it on my github account and what, I now just gave Microsoft rights to the code I don't even have? So by putting it on github I'm violating a license? It doesn't add up. The license to the code is the license to the code, no matter what site it's on and noatter what any ToS says. Otherwise what's to stop me from putting a ToS on my personal website partaining to your use of my eyeballs that says "if your creation becomes viewable by my eyeballs in any way I can use it however I want, publishing your work in such a way that it can be viewed by my eyeballs is consent to this ToS"?