I read his article less as a refutation than as a "get off my side!" argument. He seems to fundamentally agree with Gruber and MG but fundamentally disagree with their presentation of the argument. This is similar to how many of my friends and family members believe homosexuality to be immoral but believe picketing the funerals of gay people with offensive signs is awful. The Pyramid of Refutation (which is new to me and awesome, by the way) doesn't apply because the goal is not to refute.