I think opt out is stupid, but the notice is on every page of github using their banner display right now. They've also blasted out emails.

At least they are being very upfront with it (I guess?), most companies just slickly add the clause on their routinely TOS update.

If they were being honest they would ask explicitly for permission instead of advertising opt-out. Now you might ask: who will explicitly give Microsoft permission to train on their private works? No one will -- and that's the point: this is a form of theft.

And how many people who use git on github go to the website? I only do when my token has expired and I need to grab a new one to push again. Which is every 90 days. Github.com is mostly invisible infrastructure to me.