Want to know why I never trust the "protect the children!" crowd?
Almost always the people doing really harmful shit, or even very potentially harmful shit, to children are in that crowd.
They're often the type that circulate actual CSA materials as a bizarre gotcha to people they are bullying and calling pedos (as an example, remember the campaign against ao3 staff a while back were policy and abuse volunteers were getting sent this shit).
They are also frequently the ones to include graphic violence and implied or actual graphic sexual abuse in fics deliberately mislabled as General Audiences and tagged in a way that makes the fic seem like harmless fluff. All because they want to harass a group of people and don't care if children and teens stumble upon it. Technically children shouldn't be on ao3 (at least not as registered users since the ToS require you to be at least 13), and generally I say that it's up to children who do go to ao3 to be careful of what they read and mind the tags and ratings. But how can they do that if you deliberately mistag and misrate your fic.
In short, "protect the children" is more often than not a dog whistle. It can be one for the "we must control our children and everything they learn" crowd (frequently but not always evangelicals here in the US) or it can be one for the "I need a weapon to dehumanize, attack and traumatize those I dislike and this serves as both a weapon and a cover for my harassment and abuse of others. After all, I can just say I'm doing this horrible things to protect innocents even though I'm actually deliberately harming or setting up potential harm to children through my actions." Often it's a mix of the two camps. Ultimately, they don't actually care about children, it's just a nice smokescreen.