It is not impossible that the dead guy was a good guy.
We will never know.
Of course, you could take Dateline NBC's word for it. I picked up a real nice low milage pickup truck for a song from somebody who took Dateline NBC's word, once...
Wasn't Dateline the show that was putting rocket motors in the gas tanks of pickup trucks so that when they crashed, the flareup was more impressive? Hope that you didn't get one of those refurbs. :-)
It's true that we'll never know if the dead guy was a good guy, or not. I think that his actions show that he likely wasn't....but you're right, we'll never know.
IMHO, correct way to handle this is to set up a sting, then turn the evidence over to LE. Better yet, to help LE set up their stings and just report the outcome...I'd feel like it was more on the up-and-up then. That's not "Good TV", though.
I'm not sure what disgusts me the most...the behavior of the perverts on the show, the behavior of the producers of the show, or the fact that the behavior of the producers forces *ME* to defend the actions of the perverts.