In his account of this stupefyingly boring episode, Woodward -- who was obviously not present in the room -- quotes the president directly asking Calio what the word meant. In so doing, the reporter has the leader of the world's only superpower using a familiar expletive not in its literal verb sense, but in a slangy nominative similar to the usage that, when broadcast, causes great concern at the Federal Communications Commission. To my knowledge, nobody has called attention to this somewhat startling report, perhaps because the whole of Page 186 is so dull that the usual sharp eyes have glazed over.
Well, Safire is not trying very hard! Just Google the sentence Woodward quotes, and you'll get a list of mentions, beginning with the rather conspicuous article in Slate. ("Slate reads Plan of Attack so you don't have to.") The Slate article led me to discuss the quote, back here. I thought Bush was basically teasing Calio for using a ridiculous jargon word. The use of unnecessily odd words was a subject I had just commented on, after Justice Scalia used the word "reticulated" in an oral argument, and I saw Bush as someone who shared my opinion: you should have a good reason for using a weird word.
Anyway, Safire does do a good job of showing that Woodward didn't have much of a grasp on the word "vitiate," for reasons that are too boring to write, but have to do with the term-of-art use being "vitiate cloture," not "vitiate the filibuster." Safire goes on to reason that since Woodward must have misquoted re cloture/filibuster, there's a good chance he was wrong about Bush using the word the Times won't print. He's right that if there aren't known examples of Bush using the beastly old word, you ought to have a very strong source for your verbatim quote.