I never thought of it that way. I think that's because his shtick is to criticize someone (anyone!) at all times. If Al Gore were president today, Buchanan would be having a four-hour show every day in which he blabbed about Gore's inept way of handling (enter any item here) [foreign policy][the economy][China][gay marriage][the U.N.][etc.].
I will never forget Buchanan's legendary complaint about the United Nations, and how the U.S. owed no respect to a U.N. Secretary General (Boutros Boutros Ghali) "whose sense of self-importance is so inflated that we have to say his name twice."
Or his warning, on the campaign trail in 2000, to a group of Chinese journalists covering the 2000 campaign: "If I am elected President, we won't be buying any more chopsticks from you Communists for our Chinese restaurants here in the U.S."