Earlier quoted context omitted.
It's not hard to construct a "multi agent" version of the prisoners dilemma, in which only one prisoner defecting would cause every prisoner to defect.
Canonically, the Prisoners Dilema is a game with one round and each player has no idea what strategy the other player will employ; the one round is taken simultaneously. In this version, it doesn’t make sense to say “one prisoner defecting would cause every prisoner to defect.” That sounds more like the tit-for-tat strategy in multi round prisoners dilema.
No, it works in the simultaneous one-round case as well. I think you know what I mean, and it's frustrating when people reply glibly just to try and seem high and mighty online.
Let's say that all defecting prisoners are given a light sentence, and all non-defecting prisoners are given the full sentence. You can work through the rest.