Let's say that Anthropic trains their models on their internal (private) codebase. Let's say that a contributor using Claude generates a piece of code (long enough to account for copyright) that is identical to the internal closed source Anthropic ones and that code is merged into GCC. Anthropic can as well sue GCC for copyright violations and ask millions of compensation, try to explain to a judge that it's the LLM that copied the copyrighted code and you did not do it on purpose.

That to me is the reason not to accept LLM generated code, at least till the legal copyright aspects are better regulated, because for now it exposes to too much risks.