Except that he does. He only argues that two spaces doesn't look ugly in monospaced fonts but should be changed to smaller spacing when presenting variable fonts. No further explanation should be required as to why he doesn't go out of his way to break that.

He isn't trying to say "two spaces are superior", he is more saying "two spaces are more helpful for me, with my tools". Just because he prefers one form doesn't mean he hates the other.