Sure, I would bet that there are better ways to prevent child abuse than making sure that pedophiles have access to no-children-involved virtual child porn. But would it be an improvement over the current situation? I think it might; there are definitely a lot of anonymous posts on Reddit from pedophiles who use erotic fiction and lolicon hentai to suppress desires for anything involving actual children.
The broader question is: how can we improve the pedophile situation? Banning "questionable content" is politically easy, but doesn't seem to do much to protect anyone; as long as the stuff is being produced, there will be way to obtain it. It would be nice if pedophiles could get effective counseling to minimize their chances of molesting children, but currently it's very hard for pedophiles to get any sort of counseling without being reported to the police. That hardly seems ideal.
Any ideas?