The point here is that book files have to be copied before they can be used for training. Copyright texts typically say something like "No unauthorised copying or transmission in any form (physical, electronic, etc.)"
Individuals who torrented music and video files have been bankrupted for doing exactly this.
The same laws should apply when a corporation downloads torrent files. What happens to them after they're downloaded is irrelevant to the argument.
If this is enforced (still to be seen...) it would be financially catastrophic for Meta, because there are set damages for works that have been registered for copyright protection - which most trad-pubbed books, and many self-pubbed books, are.