It answers that question by replacing the Prisoner’s Dilemma with an entirely different game, which doesn’t have the awkward feature that makes the Prisoner’s Dilemma interesting.
Wei_Dai (if I’ve understood him right) is not claiming that an SI’s claim on its source code constitutes a PD, but that one obvious (but inconvenient) way for it to arrange for mutual cooperation in a PD is to demonstrate that its behaviour satisfies the condition “I’ll cooperate iff you do”, which requires some sort of way for it to specify what it does and prove it.
It answers that question by replacing the Prisoner’s Dilemma with an entirely different game, which doesn’t have the awkward feature that makes the Prisoner’s Dilemma interesting.
Wei_Dai (if I’ve understood him right) is not claiming that an SI’s claim on its source code constitutes a PD, but that one obvious (but inconvenient) way for it to arrange for mutual cooperation in a PD is to demonstrate that its behaviour satisfies the condition “I’ll cooperate iff you do”, which requires some sort of way for it to specify what it does and prove it.