First of all, I do not remember the article mentioning that he was in a pedo chat room. It could have been a normal sex chat, which is perfectly fine, both morally and legally. The fact that he asked a/s/l indicates that he was not specifically looking for youngters.
As for your assertion that there is no difference between thinking someting and doing it, well, two simple facts stand in the way of your arguement, aside form the fact that I don't find Halle Barey to be amazingly attractive. Number 1, I never clean my monitor. And Number 2, a slightly less important one, is that genies don't exist.
If they did, I can not even imagine the state the world would be in, or if it would exist at all. I have at times thought of killing myself. Not 'cause I dislike my life, but just a wierd random thought. Like when you're at the top of a building, and just think how easy it would be to fling yourself off. Now, take an educated guess, did I follow up on that idea?
I have at times thought to killing people. Probably, everyone has. But the vast majority of people don't do anything other than think it. If I'm hearing you correctly, you think that merely thinking of murdering someone is a crime in and of itself. Minority Report and 1984.
If people could get away with it, who knows what they'de do. But they can't, so they don't. If you are tye type of person who would murder or rape or whatever, knowing you won't get caught, then you are likely to try it anyways, despite the fact that you could indeed be caught.