But like any leftist, the author has shown that he doesn't know (or knows, but chooses to disregard in order to support his point) History. Two examples from the early paragraphs stand out.
Nguyễn Ngọc Loan was right to execute the prisoner in the photo that made him famous. It was a morally correct decision. Văn Lém was a terrorist, a killer of civilians (civilian women and civilian children), dressed not in a combatant's uniform but in plainclothes; and the penalty for actions like his and even far milder than his has always been summary battlefield execution upon capture. Geneva, Hague, every war-conduct treaty or accord of modern times has always acknowledged and conceded this. One might argue that the photograph of Văn Lém's death shocked America by showing the cost, the realities, of war - in the same way Matthew Brady's battlefield photos had done a century earlier - but that's not what the author of this article is saying. He's saying Nguyễn Ngọc Loan was morally wrong in his actions, and that as soon as those actions were publicized, their wrongness was apparent to all. And that's simply not true.
Author also calls out the Tet Offensive as one of the great, costly, horrific tragedies that forced America to realize that we could never win in Vietnam. And that's not true either. The Tet Offensive - the intentional breaking of a truce that the NVA itself had declared - was a tactical and strategic military disaster for Communist forces. It's only perceived as one of the horrors of 1968 because of the way Walter Cronkite sold it to the American public - one of the greatest and most successful ideologically-driven journalistic lies to date (though I expect more and worse in our future). So the author's conjuring of The Tet Offensive as a sign that the world was going horribly wrong in '68 is another blatant example of speaking from ignorance (it's either ignorance, or a lie. I'll be generous and assume the former).