Ironically, though he is quoted several times, the only words used to describe Anthony Lewis in Chomsky and Herman’s Manufacturing Consent are almost identical to those chosen by Eric Alterman. Alterman calls him “the most radical voice in the American mainstream.” Chomsky and Herman called him “perhaps the most outspoken critic of the war in the mainstream media.” Alterman seems to have misinterpreted this as an attack on Lewis by Chomsky, but the point was simply to show how the media propaganda system effectively restricts the debate. In other places Chomsky used phrases such as “the outer limits of critical independence” and “the far left of the spectrum” to describe Lewis’s position in the mainstream (in a November, 1997 Z Magazine article), but I can find nowhere where he impugned Lewis or his motives personally. One can actually agree with Lewis, disagree with Chomsky, or whatever, while still accepting his central point as valid: Had Lewis suggested that Vietnam was anything less than well-intentioned mistake, he would not have been allowed to write for the mainstream press.
I am not sure why reflexive Chomsky-bashing remains a litmus test for liberal pundits to prove their maturity, but I highly recommend Glenn Greenwald’s recent column for The Guardian “How Noam Chomsky is discussed.”