This is a very difficult topic to engage with rationally. But put the emotions aside and try.
We generally don't ban things just because they're gross. We ban child porn because children were hurt in the making of it. Without real kids involved, what's the justification to ban it, other than we just find it horrible? Again, we generally do not ban porn simply because it makes people uncomfortable. There's a lot of porn of adults I would never want to see. Hell, I don't even like porn of any kind. I'm more a romance novel type myself.
But really, as gross as it is, from a purely legal perspective, if there are no kids involved in the creation of something, how is banning simulated child porn any different than homophobes wanting to ban porn because they think gay people are gross? Again, we don't ban porn simply because we find it gross.
I could see an argument that maybe having virtual child porn out there could make pedophiles more likely to offend. But that seems like a very shaky assumption. The opposite case could just as easily be true. Virtual child porn could very well lower the rates of assault against minors. By banning it, we could very well be harming real children in the name of protecting virtual ones.