Yes, if a human saw a book enough times they would also be able to quote it from memory. They chose a very popular book which is almost certainly hugely overrepresented in training, try eg Kim Stanley Robinson's Green Mars and see if it can reproduce it in full. It's still not proper copying - and even if it was, copying is not theft, since the original person still has their original copy. Theft means you have it and the original owner doesn't. If it's ethical for individuals to copy media, it's also ethical for LLMs to do it (regardless of if they actually do)