My take on the matter is that facts aren't copyrightable. A LLM is basically recording facts.
I have a background in stylometry where you basically determine authorship by recording statistics on known pieces of writing to try to find the author of another piece of writing. So just extracting facts. You could easily now generate random sentences and filter ones that pass a certain threshold. LLMs are basically this on steroids. So it's just facts and data, not copyright infringement.
Otherwise, you'd have to argue that software reading the text contents of a book are copyright infringement.