Convicted child killer disputes warnings

Again, much like the Megan’s Law cases, I have to ask, if this man is so dangerous that you have to harass him and warn everyone in town about him, why was he ever released from prison? Aren’t early releases determined by whether the prisoner has been rehabilitated? If he is rehabilitated, than leave him alone, and if he’s not, he shouldn’t be out of jail. Why is this so hard for people to get?