And keep in mind that the $500k "contract" may have been a fiction from the beginning. Organized crime is nothing if not greedy and selfish. Why would the entire Mafia chip into a contract when only the Bonannos were damaged? And if they did, and it were found out, it'd make a prima facie RICO case even if Pistone were never damaged. My guess: Pistone made it up. Castellano went along with the fiction that he "knew about" and could "stop" the "contract" as a way of incurring some gratitude from the FBI.