Dung's problem appears to be that he's actually trying to have a discussion with you...complete with nuanced responses.
He doesn't understand you don't really care about discussion and all you want is another shot at hurling some more derision and petty taunts at him...i.e. your "poor little parrot" nonsense.
This ain't my first rodeo, Zap. I know the game. It's fun to watch. As SF's arguments get worse and worse he gets more and more condescending and snide. I think that subconsciously he realizes how fucking stupid his substantive arguments are so his lizard mind forces him to be a dick to overcompensate.