The question is not to allow something, the question is "should a free society “allow” child pornography?
Now the whole question is wrong from the start. A free society is no entity that can allow or prohibit any behaviour. The society is not an entity at all. It is a category of mind,
The question therefor is, is childpronography a crime. Now, in a free society a crime is any initiation of agression against the property of another person. Even a child owns itself, i.e. has a right not to be agressed against,no? If someone forces a child to sexual acts, this person is agressing against the child. Full stop. End of story.
Now, what do you consider worse? A child being molested or a child being killed?
In the first case, property is injured. In the second case, property is destroyed.
I would say, that destroying property is worse than injuryng it. Why? Because injured property is still property and retribution to the property owner is possible. In the second case there is no way to make good on the property owner. What follows is, that killing is worse than injuring.
How monstrous than is it to fly a B52 over an area filled with human beings, children included and drop bombs on them? As long as this is justified, that is to justify the erradication of children, just because they where born at the wrong spot at the wrong time, you better not start an argument about molestation.
Yes, molestation is a crime. Yes, it is despictable and deeply unethical. But, the very people that want to prohibit molestation, wave flags and scream in blind proudness, when their “boys” bomb the hell out of foreign people.
A free society is a society where every crime is considered a crime, and only crimes are considered crimes.