I don't know. This sort of thing will lead to stuff like recording your own memories requiring a licensing fee if not careful. I also think there's a reasonable argument that the prompter is the one creating infringement.
If someone says "imagine batman on a boat" am I not prompting what's essentially my own internal generative AI that's been trained on seeing copyrighted content at some point? If someone says "remember that scene in..." isn't that a form of recovering a copyrighted sequence from your own "trained" memories? Once there's a better ability to extract data from someone's neural activity, remembering or imagining will just be another form of prompting.