They didn’t. There is a small group of people that are always looking for the latest reason to be outraged and to point at any of the big tech companies and go “aha! They are evil!” Copilot’s ai was trained on GitHub projects and so these people are taking their turns clutching their pearls inside of their little bubble.
I’d bet that more than 95% of devs haven’t even heard of this “controversy” and even if they did, wouldn’t care.
I do think the controversy is stupid, but inside my own company, we significantly delayed migrating some projects to Github because people were concerned that the way Microsoft handled Copilot meant that Github wasn't a safe long-term host for an open-source project (and yes, I'm aware of all the reason that's irrational).
Even if the people angry about Copilot are a minority, it might still have a bad move. Trust accumulates slowly over years, but mistrusts builds up over only a few events. People are still remembering Microsoft's anticompetitive practices from 20 years ago. The mistakes it makes now might stick for a long time.
I’d bet that more than 95% of devs haven’t even heard of this “controversy” and even if they did, wouldn’t care.