Another good reminder that Hacker News is not above assuming the worst and gathering pitchfork mobs like any other social media.
The issue looked like a mistake from the start to anyone paying attention (committed by a bot, changes were consistent with a boilerplate LICENSE file being checked in).
If someone at Microsoft wanted to steal some code, forking it on Github and then publicly documenting the history of the code in the most visible way possible would truly be the dumbest way to do it.