...hatred for that which is seen as corrosive to morality. Like pedophilia is, like cartoons that are an expression of it are.
Like sexuality itself, in the eyes of the ones making the rules about who can express what.
I thought cartoons like this (if they are illegal) are covered by "obscenity" laws, specifically because they'd involve depictions of underage participants in sex acts.
Because underage characters shouldn't be "defiled" by sexual imagery. They were created to be cute and nothing beyond.
I understand it's non-logic, but that's the (generous) impression I get about things like this.
Naturally underage characters can be sexual with their integrity intact and to depict them in sexual situations shouldn't really be insulting anyone.