Pol Pot and the CPK trying to "erase the past" is exactly an example of attacking the foundations of scientific socialism. It's a dogmatic, reactionary form of agrarian communalism, not communism. I know they planned on industrializing, their approach itself was wrong and horribly misguided at best.
My issue is not whether or not the CPK believed themselves to be justified, my issue is that they were horribly wrong and acted in a reactionary manner.
As for "opposing Vietnamese imperialism," this is largely nonsense. Even if we assumed Vietnam was imperialist, the correct course would not have been to side with the US Empire, which far eclipsed any Vietnamese influence. Further, influence is not imperialism, anyone speaking of Vietnamese "imperialism" without an imperialist stage in capitalist development is making a mockery of Lenin.
The CPK was wrong. My point was never that they were evil by intention or anything, such an argument isn't Marxist. Pol Pot is wrong for similar but not the same reasons as Gonzalo, both are examples of people believing themselves to be in the right, while being entirely wrong.