That's BS. When America realized it was a political war and we we were not out to win it did popular opinion change. When it was learned that the US would not bomb Hanoi, Haiphong Harbor, or the Red River dikes the tide changed. The war had no foreseeable end. And day after day body bags came back to America. In '65 or '66 I read an article in the US News and World Reports how the war could be won in 2 weeks (there were many other sources that said the same thing). No it wasn't some small committed vocal minority that turned the tide is was LBJ who promised the war machine a war without victory. Average Joe 6 pack did not liston to the nutzoid commie pinkos rioting and looting that changed his mind about the war, it was the truth.
That's BS.
I think you need to read the entire essay. And please take your "BS" bit and stick it in your ear.