Books as lines of text are not human-consumable (by reasonable humans).
There's a strong case for sharing this being fair use, even if distributing hundreds of thousands of ebooks would ordinarily violate copyright.
I don't know what OpenAI's training corpus is or how they got it, but in case anyone has forgotten, Google has its own license-free collection of scanned books. It had already run that through OCR (and probably periodically re-OCRs) to generate its google books indexes, so there is no copyright argument against Google's book-trained AI models (assuming they train on books).
An argument that Books4 is piracy is an argument for an oligopoly on good AI models.