That is, it suggests that even if there are elements of human-generated content in a larger machine-generated work, the combined work as a whole is not eligible for copyright protection. Printed page iii of that PDF talks a bit more about that:
* Copyright does not extend to purely AI-generated material, or material where there is insufficient human control over the expressive elements.
* Whether human contributions to AI-generated outputs are sufficient to constitute authorship must be analyzed on a case-by-case basis.