But if he does have sexual attraction towards small children, then he is a potential threat. Paedophilia is a mental diorder, and paedophiles generally don't think rationally, and make up bizarre excuses to justify their actions (things like "a person reaches full sexual maturity at the age of 5"). Heck, even the book Lolita presented a situation like that. Making this guy go to a psychiatrist isn't punishing him, it's helping him, and possibly saving a poor child in the future. Igf he really is sexually attracted to small children, then he'll eventually crack if he doesn't recieve help.
Paedophilia is indeed a mental condition, but unless the person is a threat to others you can't force treatment on them. If they want treatment they will seek it out, it is not the government's place to tell them how to think.
Paedophilia is a crime because it has a victim: children. Children aren't deemed old enough to make decisions about sex on their own and therefore sex with someone who can make decisions (anyone over 18) is illegal and I totally agree with this law. Sure sometimes you get silly situations like when a 19 year old dates a 17 year old but a line had to be drawn in the sand and stuck with. But child pronography created without the involvement of any actual children doesn't hurt any of them, and therefore it should not be a crime. Just the same as rape fantasy porn with women pretending isn't a crime as long as noone was actually raped (and therefore no victim)
The bolded statement is what the crux of the whole argument is, and until you prove that anyone sexually attracted to the underaged will eventually crack without help then you are punishing someone for their thoughts and I just can't see that as something the government should do. I'm a strong believer in the old saying that your rights to swing your arms around stop at the other person's nose and therefore your rights to think should only stop when they affect others in a negative way. Until that point you can think about any crazy thing you want.