Well I can understand the other sides standpoint too. I mean, sure he hasn't done anything yet. But there are obviously a lot of cases out there where children were harmed because certain people were acting sketchy around kids, but because they hadn't actually DONE anything, they let it go. Only to have them later hurt that child. No one wants to shoulder the guilt of waiting until after someone has been hurt before they take action. I think that's what this is.

However, a lot of people that do molest/rape kids usually have some kind of history beforehand of actual actions that would point to that kind of behavior. (Not all of course, but a lot).

In this guys case though, unless he has a history of hanging around schools, bribing children with material items or touching children then they are still only policing his thoughts and fantasies. If that's the case then what about people who rape, abuse, or other equally "disturbing" fantasies? I say as long he keeps it to simply manga and cartoon characters then leave him be.