Pol Pot was not a primitivist. I seriously challenge you to quote anything that proves he is. If you count moving people to the countryside as "primitivist," then Mao was a primitivist as well.
If you read Khmer Rouge documents, it clearly says that Pol Pot thought society had collapsed and that the workers and peasants must move out into the countryside and "build" capitalism and socialism "back up." This is not the same as a primitivist and the accusation smacks of oversimplification.