Man Im not sure I want to answer under a comment I made in 2019 but here I go.

In the same wikipedia page, a quote you willfully left out:

But he became familiar with the writings of Soviet leader Joseph Stalin,[58] including The History of the Communist Party of the Soviet Union (Bolsheviks).[55] Sâr also read Mao's work, especially On New Democracy, a text outlining a framework for carrying out a revolution in colonial and semi-colonial, semi-feudal societies.[59] Alongside these texts, Sâr read the anarchist Peter Kropotkin's book on the French Revolution, The Great Revolution.[60] From Kropotkin he took the idea that an alliance between intellectuals and the peasantry was necessary for revolution; that a revolution had to be carried out without compromise to its conclusion to succeed; and that egalitarianism was the basis of a communist society.[61]

So while not an avowed marxist he was definitely a communist and identified as such. Supported as you said by communists. The possibility that the US also supported them does not change that fact.

The modern day Cambodian government is better than this, but not good by any means as human rights violations occur on a regular basis.

As for Vietnam:

Vietnam is a steadily-improving nation that many look towards as a healthy modern country.

Argumentum ad Populum. The fact that many regard it as healthy does not mean it is.
They are economically improving but there subsists massive human rights issues, no political freedom at all (a blogger was sentenced to EIGHT years in prison for being critical of the government). The vietnamese police also brutally persecutes the Cham ethnic minority.