if it is not law enforcement, no I think it is a bad idea to have someone trying to bait people online.
I know the police are not perfect, but I don't think posting pictures and other information of people that one person says is a potential pedophile. Who is this person? How can you trust someone who does stuff like that?
It sounds pretty damn creepy to me...and yes I have kids, but I don't belive in the end justifies the means because how many innocent people get put on the site because someone else sends their photo and contact information. That is just too easy to fake, people. How many times have you got an email from someone you know...but it wasn't really them? I have had my email address "hijacked" before if you will...at least law enforcement SHOULD have the money to figure out where messages are really coming from.
Here is another thing as well....let's say they do post some one that may be dangerous on this site. What's to stop that person from taking it out on the person who put up the website? I love the internet, but you have to take these kind of sites with a grain of salt...
If this person is really sincere I respect the intent, but I think the execution of this idea is a BAD idea, and I won't click on the link...just my opinion.