I am nonplussed. That seems to me a prime example of the 'orphan fallacy' (a defendant convicted of parricide asks for leninecy on the grounds that he is an orphan) in reverse.
The communist coups occurred precisely because the ancien regime was (i) extremely backward and (ii) unwillling to implement democratic reform (cf. Barrington Moore, _The Social Origins of Dictatorship and Democracy_ also Jeffery Paige, _Agrarian revolution : social movements and export agriculture in the underdeveloped world_).
Stated differently, a revolution is the outcome of and the response to the backwardness and oppressiveness of the ancien regime. In that context, blaming the commies for the method of of social change is the most reactionary bullshit I've heard for some time. What's next, blaming the Jews that they provoked the peace-loving Nazis?
Another point: I can cite a handful of cases of democratic regimes being overtuned by a consortium of capitalists in alliance with fascists, or by supposedly 'democractic' government of the United States. I challenge Professor DeLong to cite a single example of a democractic regime being overturned by a communist coup with or without aid from the x-USSR..