They are confusing personal disgust with a sense of morality.
Yes! This!! This is exactly the thing. And it's a shame because personal disgust is so very not a good moral compass.
Even when it comes to, say, loli/shota stuff (kinks that in my mind are not meaningfully different from pedophilia itself), the response I often see on the internet seems like some kind of virtue signaling that I don't understand.
Because even if you can connect the dots between a kink and the concept of childhood there is still a meaningful difference between pedophilia (thoughts) and child sexual abuse (actions). I'm not saying to be uncritically permissive of thoughts -- thoughts may not always lead to actions but they do always precede them. But if a community is so hostile to the concept of pedophilia that people who are struggling to find positive ways to handle the problematic parts of their sexuality can't even talk about them... well maybe that was less about preventing harm, and more about feeling self-righteous.
If you care about protecting children, and I'm assuming you do, it's worth taking an honest look at the problem. Be real about where harm comes from. Overwhelmingly, it comes from family members, gym teachers, priests, creeps in your kid's DMs, and the Epsteins... not artists on Pixiv whose favorite fictional character ships happen to also be teenagers.