In practical terms even if it is illegal there is no reason you would ever be caught creating AI porn for personal use, as long as you create it locally.

I think it is an interesting question: why should something be forbidden if it doesn’t directly harm anyone?

In my opinion, it comes down to people feeling unsafe because this kind of media is consumed by other people for (sexual) pleasure. A lot of people in our society had experience with sexual abuse and rape - especially for women the numbers are extremely high. If media with this kind of content is consumed by people for sexual gratification, it may make victims of rape feel very unsafe.

Maybe I can bring an analogy from my own life to clarify my point. I love wearing skirts regularly, most of them are mini skirts. I would feel very unsafe if I would know that one of my friends watches videos of upskirting, even if they are created by an AI. For me, that means that I won’t feel safe around them. Of course you can say “well, but why are you scared of them; they aren’t filming under your skirt, right?” And while I agree, I had my fair experience with catcalling: too many people in society don’t respect my right to wear skirt the way I want them. If I would know a friend watches this kind of content, I would doubt if I can really be safe with them.

I think it isn’t unplausible to assume that for a person who has been sexually abused, knowing that some people enjoy this kind of content would make them feel very unsafe. In case of porn, this usually is media we consume privately and don’t share with others. So no - while I don’t think the act of watching AI porn per se is harming anyone, the consequences for victims of rape absolutely do.

I hope this makes sense.