Even accepting that, the law should be encouraging creative output by individuals and there is justifiable fear that this will be used to bypass protections designed to reward such behavior.
For a more direct counterexample, I can memorize something and type it back out, but if it is copyrighted the law doesn’t make an exception just because it passed through my head.
If the AI is able to type back out a duplicate of the training data, then I agree that's copyright infringement. If it just learns from the data like a human with normal memory reading a large amount of material, then I don't see it. That's normally the case. There have been experiments where someone managed to make an AI spit out near-copies, but it's not the default situation and seems preventable.
I do agree that we should encourage human creativity. But if AI isn't making copies, and the output of AI isn't awarded copyright (as is currently the case) then I think humans still have sufficient reward.
For a more direct counterexample, I can memorize something and type it back out, but if it is copyrighted the law doesn’t make an exception just because it passed through my head.