are you saying that selling a book that has the same characters as a recently released book doing the same things but with wording differences is somehow fair use? Like a book called Harry Potter and the Something Rock with the exact same plot points but worded slightly different is fair use?

no. I was saying selling an AI model or access to it that is capable of producing that work is not, itself, copyright infringement.

in fact, do you know what a clean room is? if I provided to a writing team every English language work except those written by JK Rowling and it produced a work exactly like you're describing, The resultant work would not be infringing copyright. it should not be any different for AI where you cannot prove what materials it was provided.