I find King’s virulent leftism extremely strange. He of all people should know the danger a controlling, all-powerful government poses to the average Joe.
I think it's more that King has always been contemptuous of conservatives, who he views as crazy religious fundies, "Carrie White's mom" types always trying to cram Jesus down everyone's throats.
The thing about these people is that they've never seen true brutal Leftism in action. They weren't living in Cambodia during Pol Pot's regime.