Thanks for responding.
1 - What's some appropriate phrasing for comparing an underage fictional character to a legal nude photo (i.e. a photo of a legal age model who just happens to look young)? Is it enough to put "legal model" somewhere in the text?
2 - Cool. Mentioning model names is also nice for people who want more of her.
3 - If an image contains a studio watermark or a pornhub ID, is that sufficient sourcing?
Again I don't expect this to be a problem but having clarity helps ensure that.
The issue you run into here is that you're not trying to satisfy the mods - you're trying to satisfy the mods idea of satisfying the FBI. That's two levels of interpretation away. QQ can insulate itself from this kind of liability in the same way that KiwiFarms does. You declare yourself an open platform, allow anyone to post anything, and then whatever they post is strictly on them, and if they post kiddie porn the only thing QQ has to do to cover its ass is delete it when they get the court order and forward the details of the offender. QQ has chosen not to do that, because they like to police content such as politics, which makes them an editor, which means any kiddie porn that gets published has their assumed approval under the law since they didn't take it down. That necessary vigilance and liability is the price you pay for wanting to control what's on your platform. Taking authority causes you to have responsibility, and disclaiming authority absolves liability provided you don't then exert authority anyways.
However since the FBI already has all the kiddie porn in their database and are the ones seeding it to catch people,
not actually being kiddie porn will save you from the FBI because they'll know it's not in their database and so it's legal. But it won't save you from the mods
wondering about what the FBI thinks, and nuking your ass to make sure theirs doesn't go to jail.
So 1: Don't. Don't say an underage fictional character is depicted by a legal nude photo. This makes people wonder, and may violate the "indistinguishable reproduction" clause that stops deepfakes and hyper-realistic CGI of minors. Don't make people wonder. Staff can't afford to wonder.
and 3: Probably not. Anyone can shop a watermark. It's
reasonable that studio sourcing proves age, since they
also have to prove age. But you have to prove
sourcing, and 9gag and Ebaum are proof that watermarks don't prove that.
It is an affirmative defense to child pornography only if
EITHER The "They're legal!" Defense.
You can prove there are only adults,
AND
You did not advertise them as minors,
SO saying your fictional minor is represented by this legal real image fucks your "they're legal" defense.
OR ELSE The "Oh shit!" Defense.
You possess less than three such images,
AND You immediately
report,
AND
destroy,
AND
retain no copy,
AND
have not shared,
any such images,
SO posting it on a forum fucks your "Oh shit!" defense.
The "Oh shit!" defense is also your affirmative defense for everyone who
doesn't have any child porn, because reporting and destroying and retaining no copy and not sharing all zero images is already done.
Disclaimer: I am not a lawyer and this is not legal advice.