In the link, he says he never thought those things before. Well, he obviously HAD thought about a child in a sexual way before. Otherwise, how could he know he was always attracted to children? If you don't have any desire, you don't know you are attracted. Pedophiles can't just strike up a relationship with someone. The only means to their desires, are to molest. The escalation, I believe, is them simply justifying their behavior along the way. So, there is no problem luring her. He has convinced himself in every step of his deviancy, that what he is doing is not wrong. With these unintelligent and messy pedophiles, they often just freak out and have to murder. They know society thinks what they've done is wrong. Yet, they are happy with what they have done, they inject themselves into the investigation. Both to make themselves look innocent, and because it's part of the thrill.
I believe molesters are no different then any other person, who justifies their behavior, step by step. Look at Jerry Sandusky! He justified his behavior as love, and that he was helping poor kids. He was intelligent, and could groom a child not to talk. He could fool everyone around him. TH and killers like him, can't do that. Molesters and child killers are the same as any criminal, who justifies their behavior. EVERY criminal has the ability (unless they are legally insane) to control their impulses. Escalation, in my opinion, is justifying their impulses, until they get what they want.
It's not rational to me, but it's the way people who are irrational justify their behavior. IMO.