The quote was:

I think it's right to cooperate in this thought experiment only to the extent that we accept the impossibility of isolating this thought experiment from its other possible instances

I agree with one direction of implication - if we accept the impossibility of isolating this thought experiment form its other possible instances (e.g. cases with the exact same wording but with paperclips and staples swapped) then it's right to cooperate.

If we don't accept that then I will admit to being confused and have nothing meaningful to say either way. I accept the "least convenient world" principle for when someone suggests a really bizarre thought experiment, but I'm having trouble with the concept of "least convenient set of possible counterfactual worlds". Is this concept worth exploring in its own right?