Wouldn't copyright infringement with AI only apply if you try and sell a product or make money with it? I would think OpenAI would just insert some disclaimer making the user responsible for the final use of the image or output, since anyone can make fan art and that, I don't think, is infringing any copyrights. I would see no difference between generating fan art, and actually making it, so it's on the user to understand how they are using the tool.