I think it's true that people felt compelled to get rid of foreign influence in their country, after being an occupied nation for so long. I can also see why they'd frame it as being free from "exploiters and bourgeoisie," as communism and socialism were certainly gaining traction during that time period. However, I think that in any society some will always be exploiters and some will always be better off than the majority of the population (making them bourgeoisie in some people's eyes), so in some respects Sang's reasoning is naive.
If the US hadn't gotten involved I still think the country would have had a revolution that killed a lot of people, and likely would have ended up with the same system of government it has now. Fewer people would have died, the country wouldn't have experienced food shortages to the same extent, and certainly no one would have been impacted by Agent Orange.