I don’t think it makes sense to talk about these systems as though they have any agency (and I think I was careful not to).

Of course there is nothing that necessitates letting these systems do what humans do.

What I am saying is that I am allowed as a human to ingest copyrighted material, learn from it, form mental abstractions and use those learnings to generate new art. Why then, would I be forbidden from externalising some of that process into an artificial system that operates on similar principles.

The trained model obviously does not have agency. It is a creative and computational tool, much like any other digital tool or product.