If a deterministic machine transformation from a copyrightable prompt results in an uncopyrightable image, what do you think a compiler is doing to source code?
a compiler on the other hand is generally pretty deterministic. The non determinism that we see in output is usually non determinism (such as generated dates) in the code that it consumes.
I'm not saying AI art should or shouldn't be copyrightable. One can argue the inputs into the AI generator are copyrightable, but if the output isn't deterministic translation of the input, its a different argument.
"The courts just take issue with him naming his AI system as the sole author and himself as the copyright owner."
you can't claim a non human as the "author" and claim the material is copyrightable.
the "author" (not the AI) was trying to make a legal point/hack and the courts shot him down.
Review and testing do not confer a copyright the work reviewed or tested