If a savant has perfect recall, remembers text perfectly and rearranges that text to create a marginally new text, he'd be sued for breach of copyright.
Only large corporations get away with it.
Any suits would be based on the degree the marginally new copy was fair use. You wouldn't be able to sue the savant for reading and remembering the text.
Using AI to creat marginally new copies of copyrighted work is ALREADY a violation. We don't need a dramatic expansion of copyright law that says that just giving the savant the book to real is a copyright violation.
Plagarism and copyright are two entirely different things. Plagarism is about citations and intellectual integrity. Copyright is a about protecting economic interests, has nothing to to with intellectual integrity, and isn't resolved by citing the original work. In fact most of the contexts where you would be accused of plagarism, would be places like reporting, criticism, education or research goals make fair use arguments much easier.