I think the article makes a lot more sense when paralleled with the cover article of the same issue:
http://www.theatlantic.com/doc/200810/mccain
which attempts to continue the Vietnam/Iraq analogy into parallels between McCain and his father, who remained optimistic about Abrams' improvements in Vietnam up until Saigon fell, with the implication that "your father was grossly wrong about South Vietnam, isn't the same true about Iraq?"