These are two sides of the same coin, and what I'm saying still stands. This is talking about who you attribute authorship to when copyrighting a specific work. Basically on the application form, the author must be a human. The reason it's worth them clarifying is because they've received applications that attributed AI's, and legal persons do exist that aren't human (such as companies), they're just making it clear it has to be human.

Who created the work, it's the user who instructed the AI (it's a tool), you can't attribute it to the AI. It would be the equivalent of Photoshop being attributed as co-author on your work.

Couldn't you just generate it with AI then say you wrote it? How could anyone prove you wrong?

That's what you're supposed to do. No need to hide it either :).