I think that's what Vidal is trying to say here:
While contemplating the ill-starred presidency of G.W. Bush, I looked about for some sort of divine analogy. As usual, when in need of enlightenment, I fell upon the Holy Bible, authorized King James version of 1611; turning by chance to the Book of Jonah, I read that Jonah, who, like Bush, chats with God, had suffered a falling out with the Almighty and thus became a jinx dogged by luck so bad that a cruise liner, thanks to his presence aboard, was about to sink in a storm at sea. Once the crew had determined that Jonah, a passenger, was the jinx, they threw him overboard and—Lo!—the storm abated. The three days and nights he subsequently spent in the belly of a nauseous whale must have seemed like a serious jinx to the digestion-challenged whale who extruded him much as the decent opinion of mankind has done to Bush.
This dude, Vidal, can write.
UPDATE: On second reading, it seems Vidal could have meant 'Bush == Puke'.