If someone released a chatGPT/characterAI with NSFW content enabled it would eat into a big share of their users (and for characterAI, maybe take all of them). Seriously, look into what people are posting about when it comes to characterAI, and it's 80% "here's how to get around NSFW filters". Unsure why nobody is taking this very very obvious hole in AI tech.
Stable diffusion no longer uses even adult NSFW material for the training dataset because the model is too good at extrapolating. There are very few pictures of iguanas wearing army uniforms, but it has seen lots of iguanas and lots of uniforms and is able to skillfully combine them. Unfortunately the same is true for NSFW pictures of adults and SFW pictures of children.