Your position is giving very much a free pass to the atrocities the U.S. government was responsible for at the time. Chomsky was one of the few voices that saw it, and denounced it accordingly. His position on Pol Pot has never been fully absolutory, instead he just focused more on the injustices coming from his own camp, where he certainly had more weight to excert. Also, Marxism is a perfectly fine philosophy, and extremely interesting lens through which we can read and understand capitalism and our present. Conflating Marxism/Communism as one thing to reinforce a negative bias against them unfortunately shows a profound misunderstanding of both