I can buy Vietnam as a "noble conflict" to a point...but only on a very superficial level.
The Geneva Conference called for the end of the partition of the country in the mid 50's following elections. "Our guy" Diem, appointed by us but with strong nationalist credentials (so not an unreasonable choice), cancelled the elections when it became clear that the communists were going to win (as President Eisenhower said, "80 per cent of the population would have voted for the Communist Ho Chi Minh"). Diem then (some ally) started ignoring us and taking military action against his political opponents.
They then later held an election so rigged that Diem literally had, in Saigon, about 130% of the city's population voting for him (he won by 98% in the country as a whole). The South increasingly became hostile to Diem, and Diem responded with torture, executions, and general paranoia. His regime was under greater threat from internal coups than it was from the communists, which is why the U.S. began to fear he'd cut a deal with the north once the election had solidified his "legitimacy." It's also why we backed the generals who eventually staged a successful coup against him (and murdered him).
Our ally...murdered by the insurgents that we plotted against him with. Not exactly the "noble" stuff. The resulting government failed and fell, as did several others. All of them were viewed as American puppets and the population's support for the communists rose steadily.
I think, more accurately, Vietnam was a localized use of the containment policy that otherwise served us well. We appointed Diem because he was catholic and staunchly anti-communist. We then looked the other way as he cancelled and rigged elections because we didn't care what the people of Vietnam wanted--we wanted to halt the advance of communism (in part because of a mistaken belief that the north Vietnamese were puppets of the Chinese). When we no longer cared for Diem, we backed a coup to put other anti-communists into power. The net affect of the political turmoil was that support for the communists ultimately stayed pretty high, and some people became increasingly militant.
So it wasn't exactly as if the nation of South Vietnam cried out to be saved from communism, it was that we kept backing leaders who were anti-communist, because *we* wanted south Vietnam to be non-communist. Other than that, I doubt we cared if they turned to totalitarianism, as long as they were "our" totalitarians.
That is, to be sure, the standard view of the history of the conflict, but assuming the people in the history department believed that to be the truth, then wouldn't anyone who viewed Vietnam as a "noble cause" be seen as sort of a simp? Would you hire someone you thought to be a simpleton just for the sake of diversity? What's next, have a special position for the Holocaust deniers? They have a point of view too.
