I don't think anyone would say you should be prevented from drawing whatever you want in a sketchbook. But if I started distributing a magic sketchbook that drew one particular person in lewd poses, even though those images don't exist yet when the sketchbook is distributed I could see a strong argument that what I'm doing is essentially harassment and defamation. The US doesn't have federal protection of image rights (that I know of, anyway) but depending on the state it may be illegal to use someone's likeness in this way.
I do think that there's an argument here that could be brought before a court and potentially won that even if individual lewd images are free speech, creating and distributing a machine that produces those images can cause real material harm to the person whose likeness is used in the imagery.
not creating. Only distributing could create harm. So if someone wishes to create AI generated imagery in private, without giving said image public access, then it ought to be fine.
I'm not sure that distributing alone is in fact harmful, otherwise you could sue everyone in the pipe that touches the bytes. Both creating and distributing together create the necessary conditions to show intent and harm.
I do think that there's an argument here that could be brought before a court and potentially won that even if individual lewd images are free speech, creating and distributing a machine that produces those images can cause real material harm to the person whose likeness is used in the imagery.