I wonder if there exists any system in place that this could backfire rapidly if this could be proved on some level. Unfortunately, world needs examples and consequences before anything changes. If this worked for this particular engineer, others will follow and will attempt the same. It will become a norm in big corps.
Causing a legal shitstorm is most likely not a sustainable way to get ahead at big corps.
If this is what happened, I suspect Microsoft will drop this person even quicker than a hot potato, and even quicker than if they told them to rewrite it from scratch but the person took a few shortcuts too many (which would be my guess).
If they wanted to fork it, they could - just keep the attribution and be done with it. The fact that they tried to rewrite it suggests that someone wanted it to be legally not a copy.
