The concern related to copyright is not that the AI labs would assert copyright over the code produced by their LLMs - that is a complete strawman.

The concern instead is that LLMs and all of their outputs may be found to be derivative works of their entire training set, and thus rendered unusable (as the training set is not distirbutable under any license).

I think this ship has long sailed and no court is going to dare give such a decision given the money involved, for better or for worse. But it's a much more realistic scenario, in principle, than LLM labs going mad and attacking their own customers.

Edit to add: there is another, completely different, copyright risk associated with LLMs - and one that is much more realistic. It is the fact that code generated by LLMs may not, in fact, be copyrightable at all. Which would mean that it can't be subject to the GPL. As long as it remains a minority of GCC code, this wouldn't matter much, but it could in time lead to significant portions of GCC becoming public domain, and thus cooyable, modifiable, and redistrubutable without providing the four freedoms.

In many timelines, non-copyrightable code in GPL project doesn’t restrict the user’s freedom, since an LLM can easily reimplement the functionality clean-room. AI has brought levels of freedom to users that GNU could never do. Practical levels of freedom, leading to real, positive outcomes. Software is finally free in the real world.