All these are public quotes by Stallman:

The [federal court] nominee is quoted as saying that if the choice of a sexual partner were protected by the Constitution, "prostitution, adultery, necrophilia, bestiality, possession of child pornography, and even incest and pedophilia" also would be. He is probably mistaken, legally — but that is unfortunate. All of these acts should be legal as long as no one is coerced. They are illegal only because of prejudice and narrowmindedness.

I am skeptical of the claim that voluntarily pedophilia harms children. The arguments that it causes harm seem to be based on cases which aren't voluntary, which are then stretched by parents who are horrified by the idea that their little baby is maturing.

There is little evidence to justify the widespread assumption that willing participation in pedophilia hurts children.

I've read that male dolphins try to have sex with humans, and female apes solicit sex from humans. What is wrong with giving them what they want, if that's what turns you on, or even just to gratify them?