OK, personally I don't think such honey traps should be legal, you can never say for sure, that a person falling for it, would use an illegal site if the honey trap didn't exist.
IMO it's immoral, and luckily in my country they are in principle illegal, although the police here is trying to push the line on that.
The honey trap could be the thing that "ignited" the interest for an individual!
It can also be the trigger for other people to make similar sites, as in if they can do it, we can do it too.
Honey traps break with the fundamentals of justice in many ways, and making them legal is a sign of a sick society IMO.