Companies aren't monolithic entities, MS has tens of thousands of employees. Just because the upper level of the upper level of upper level management (which is a different group of people than engineering) might have been hostile towards it years ago doesn't mean that everyone there agreed with that stance, and it doesn't mean that that management culture has persisted to the present day.
Ultimately the only thing that matters are actions, not the human personality traits that people project onto anthropomorphized corporations. I'm sure there are plenty of people there now that are anti-OSS, and pro-OSS, and everything in between. It doesn't matter. All that matters at the end of the day is what software is released and how that software is licensed.