Hence the accusation of entrapment. Nobody here knows the full story, since none of us are lawyers or cops involved in the case. People hear pedophile and have this strange need to threaten violence, perhaps out of some unconscious desire to prove that they are moral citizens.
Paedophilia is an illness that many people do not act on. Being strung along by a police detective is a bit questionable. This is not to say that he was in the right trying to meet up with a 13 year old.