Leave it up for anyone to download and then compensate the copyright holders later.
In fact if ingesting these books for LLMs is fair use, us commoners should be able to read them for free. Maybe restrict commercial redistribution though.
> They should be forced to publicly release the books as an Ebook.
would be reasonable in any way? The books aren't theirs to release publicly. If I brought a copy of any given movie on DVD, ripped it and used it to train my own "LLM" located at /dev/null, should I then be allowed (or even forced) to release the movie publicly for anyone to watch for free?
Set up a compensation fund for the rights holders. Anything is better than culture literally being sucked into the void.
But that's a larger problem that encompasses single use packaging and all the other plastic garbage we're producing all the time.