We keep asking what the consequences and possible harm are, and asking for the evidence that led you to the conclusion that these consequences and possible harm are serious enough to merit government intervention, but we don't get any clear answers.
Oh, let me play the devil's advocate if he won't
1) the kids will be ridiculed and ostracized by their peers
2) their friend's parents will not let their children associate with children of such obviously low moral character
3) perverts will look at the pictures and masturbate
4) perverts will seek out the children and try to molest them
5) parents will coerce children to pose against their will
6) Even if the children do consent, they will realize what a terrible thing they have done when they grow older, leading to severe psychological damage, drug and alcohol abuse, promiscuity,
godless communism, and eventually suicide.
7) they will be hounded by do-gooders and religious fanatics wanting to protect them from exploitation and help them save their souls
8) those that are Muslim may be subjected to honor killings by family members
9) they may cause the western world to realize that nudity is not such a big deal, causing the rest of the population to start walking around nude. This will have the twofold effect of plunging the world economy into recession as clothing sales plummet and dramatically increasing the incidence of skin cancer.
and most importantly
10) Put on a sweater! You'll catch your death of cold!