Might still be valid for closed source projects (probably is).
I think courts would need to weigh in on the open source side. There’s legal precedent is that you can use a derived work to generate a new unique work (the spec derived for the copyrighted code is very much a derived work). There are rulings that LLMs are transformative works, not just copies of training data.
LLMs can’t reproduce their entire training set. But this thinking is also ripe for misuse. I could always train or fine-tune a model on the original work so that it can reproduce the original. We quickly get into statistical arguments here.
It’s a really interesting question.