Or they might conclude "even an AI could come up with this, it's obvious". Obviousness is a defense in patent law, not in copyright law.

There is a fairly effective counterpoint here that information is worthless if nobody can find it. Generating a handful of useful designs in a sea of pointless ones doesn’t count as ‘coming up with it’. Remember that a description of every idea already exists in the Library of Babel. I do not think that AI generation without curation really counts as ideation.