The defection test is the framework’s guard against transition designs that only work if everyone cooperates. Many desirable safeguards create vulnerability if adopted alone: an economy that protects standing competes against one that keeps brutal labor costs; a society that limits surveillance competes against a state that gains advantage through total surveillance; a developer that paces itself competes against one that races. So every transition project has to answer, up front, what happens if another participant refuses? — and either remain viable under defection or be paired with enough preserved advantage that restraint is not self-defeating.
This is realism, not cynicism, and it is the same constraint the framework already meets in ownership concentration (why would powerful owners agree?) and strategic competition (coordination among rivals who trust each other least exactly where the stakes are highest). Making the question standard keeps the framework honest: a beautiful architecture that assumes goodwill it cannot guarantee is a description of a better world, not a transition into one.