I hear you, but I think you might miss my point, which is while LLMs are clearly trained on copyrighted material, what they produce (their output) is NOT a copy of a specific code snippet they were trained on in a way that you would say "that's a copy from this code base".
Thanks for that link to the definition and requirements for something to be considered a derivative work.
I think my interpretation, based on your link, holds: unless the LLM output (transformation) substantially bears the original source code author's creation and personality, there is nothing to give attribution to.
I will continue to hold that position until such a time that we get a better answer than:
> we cannot rule out that de-identified data derived from their usage of our products helped improve our models