Couldn't this guy argue he knew the "kid" wasn't actually a kid and he thought they were roleplaying or something? It would actually be kind of believable in this case.
Another thing that always surprises me is when Hansen does his have a seat thing, why don't the guys say "No, fuck you and I'm not signing the release so don't even think about airing this on tv!" Why would they give an interview and provide the DA's office with ammo against them? Shouldn't a criminal know that as soon as you're busted you shut up and ask for a lawyer? I'm not a criminal and I know this from just watching tv.
He arrived with the pretense of the person being a child. I think they actually use children's photos for these so I don't think this guy could have talked his way out of it.
I'm not sure how the criminal processing and TV releases work in this situation. I know there have been people who don't take a seat and just take off running but the police obviously catch them when they are outside. The show already has a lot of ammo against them. If they sign a release or sit down and talk maybe they get some sort of leniency. Another thing that could be happening is that the criminals are so caught off guard by being surrounded by cameras and confronted by a grown man that they just sort of comply.