It could stem from the time he was trying to make Revenge of the Sith seem deeper than it really was.

“That was the period where Nixon was trying to run for a [second] term,” Lucas told the Chicago Tribune in 2005. “[That] got me to thinking historically about how do democracies get turned into dictatorships? Because the democracies aren’t overthrown; they’re given away.”

Then the later interview with James Cameron seems to be the source of the Viet Cong idea which he probably just made up there and then to sound cool in front of the camera. Unless the Making Of books have anything in them to back this up.