The fight against the Vietcong terrorists - and they were terrorists at first - was separate from any religious strife.
The difference between you and I is that I was there on the ground during the Buddhist riots of 1966 and saw what the issues were. I served a total of 15 months, including direct combat in Vietnam, so I know who was our enemy and who wasn't. The Buddhists were never part of the problem - that was Saigon's problem. The enemy was the Vietcong regulars and the North Vietnamese divisions in the South - and the full weight of the Logisitic support of the Soviet Union, China, and the Warsaw Pact.
You've been listening to the enemy's version of history.
I understand your perspective, but their is another perspective also with much truth.
The French Catholic church had their own military/police force that was actually murdering unarmed peaceful Buddhist monks.
And since it was Diem’s brother heading the Catholic Church, it spread to the government too.
Buddhists were considered second class and not able to get government jobs. They were suppressed, and as such turned to Ho to try and get out of the suppression. They drove them to communism.
I had relatives there in the 1950’s and early 1960’s as advisors.
Failure to recognize that the Buddhists were against the US and French greatly effected the final outcome of the war.