I once asked a senior American official about why he accepted honoraria from the Mujahedin-e-Khalq, or the MKO, given the group’s cultlike nature and its lack of popularity inside Iran. His response: Even if the group lied about its support, they said the right things about democracy and regime change, and so he saw no harm in collecting the cash. The regime’s fall, he said, would be a moment of truth: Either the MKO would prove itself right, or its political Ponzi scheme would collapse. The problem with engaging in the MKO’s endorsement-for-cash scheme is the impact it has on...