It seems basically that LLM output is public domain, but a bit of human-generated content can be mixed in (whatever is enough to pass the "threshold of originality") and then the overall work can be copyrighted. Much like republishing a public domain book and adding an introduction or a few footnotes (but harder to extract the public domain component.)
But this all says nothing about the original question, about whether the weights can be copyrighted.
But this all says nothing about the original question, about whether the weights can be copyrighted.