While humans don't have encyclopedic memories, our brain connects a few dots to make a thought. If I say "Luke, I am your father", it doesn't matter that isn't even the line is wrong, anyone that's seen Star Wars knows what I'm quoting. I may not be profiting from using that line, but that doesn't stop Star Wars from inspiring other elements of my life.
I do agree that copyright law is complicated and AI is going to create even more complexity as we navigate this growth. I don't have a solution on that front, just a recognition that AI is doing what humans do, only more precisely.
(that's all to say copyright is dated and needs an overhaul)
But that's taking a viewpoint of 'training a personal AI in your home', which isn't something that actually happens... The issue has never been the training data itself. Training an AI and 'looking at data and optimizing a (human understanding/AI understanding) function over it' are categorically the same, even if mechanically/biologically they are very different.
I think that's the conclusion of the judge. If Anthropic were to buy the books and train on them, without extra permission from the authors, it would be fair use, much like if you were to be inspired by it (though in that case, it may not even count as a derivative work at all, if the relationship is sufficiently loose). But that doesn't mean they are free to pirate it either, so they are likely to be liable for that (exactly how that interpretation works with copyright law I'm not entirely sure: I know in some places that downloading stuff is less of a problem than distributing it to others because the latter is the main thing that copyright is concerned with. And AFAIK most companies doing large model training are maintaining that fair use also extends to them gathering the data in the first place).
(Fair use isn't just for discussion. It covers a broad range of potential use cases, and they're not enumerated precisely in copyright law AFAIK, there's a complicated range of case law that forms the guidelines for it)