Some quick thoughts. It seems that Chomsky is worried about losing the critical universality that grounds political analysis; a condition, presumably, of any socialist revolution. But without examples it does seem to be somewhat bitter, decrying faddish-but-incoherent theorization as some kind of major "cause" of stalled third-world revolutions.
There were certainly leftist insurgencies over the last half-century powered by "postmodern" thinkers -- the Italian movement Autonomia seems like a quite plausible candidate here, associated with Antonio Negri's "workerism" and being strongly influenced by various strands of post-Marxism and situationism, etc.
There are certainly political dangers to "generalized relativism" and speculative detachment. But postmodernism is probably not best summed up this way; and may be better understood as a variegated family of experimental movements than as some holistic "unified field theory".
It may help to keep in mind that movements like situationism conditioned not only new aesthetic and logical relations "in theory" but also new forms of life, new capabilities and opportunities for social transformation; and have been instrumental in raising mass consciousness about the bad economic determination of existence under capitalism.
If you're worried about the decline of the left generally, or that postmodernism has left the universalism of "serious Marxism" in ruins: Lenin still walks around the world; and the strangest tongues still do understand him. (Consider maybe also here that postmodernism is also often a likely scapegoat for the right, existing today largely as an excuse to interrogate the "leftist" academy about its curriculum corrupting the youth...)
