There are some odd choices on that list. Heinlein didn't "move toward" in the 1960s... he always had that tendency. Yet he was also, for much of his earlier life, a Democrat, and always a socialist (albeit not of the type most people think). Howard tended toward the anarchic. Lovecraft, though a staunch conservative in his early years, moved well toward the other end o the spectrum in his last decade (the period during which he did the bulk of his "Cthulhu cycle"), even to the degree that he felt FDR was far too conservative for his liking. Look at the "ideal" civilizations he depicts for his alien creatures; they were socialistic. And his "monsters" represent a much more intricate complex of symbols than is perceived here. (He would also have been rather flabbergasted at being compared to Russell Kirk, even in this fashion....)
Still, an interesting list... though I think I would add Moorcock's Col. Pyat novels or The Brothel in Rosenstrasse as well.....