Not necessarily disagreeing, but just to be Devil's Advocate for a moment: what would be his motive in confessing to a crime he didn't commit? Yeah publicity is one thing, but there's an excellent chance he gets the death penalty if convicted. He probably is mentally disturbed, frankly I think all pedophiles are, but I don't recall any other high profile case whereby someone eagerly confessed and it turned out they were innocent.
For an arrest, I would imagine it would take more than just some pedophile in Thailand saying "I did it". I would think there would be more evidence that has not yet been made public. I mean I've heard of people walking into police stations and confessing to crimes but they're not taken seriously unless there is other compelling evidence. I can't imagine him being arrested without some other evidence besides a confession.
But then again, this is the Boulder police and they haven't really distinguished themselves on this case.