It'd be nice to see some proof here. Copyright is not absolute and does not extend, for example, to things that have no creativity in them. There are only so many ways to write a for loop or an if condition. Training an ML model from a large body of code IMHO violates copyright no more than any of us reading code and learning from it, as long as GH Copilot doesn't spit out code that's exactly the same as something already existing.