"I think if the story told by O'Neil and the Swiftvets were somehow conclusively proven to be true in a way that not even Terry McAuliffe could dispute, then Chris Matthews' head would explode."
I think the book is already out with commentary from Kerry's ENTIRE chain of command, including Admirals and Captains (the Naval equivalent of a full bird Colonel) and from eyewitnesses on nearby boats. If that's not proof positive, what is?
Nonetheless, the left will continue to ridicule the entire story and discount the possibility that it could possibly be true, just like they did with all the stories about Klintoon and Hitlery.
I'm not doubting the veracity of the book and its claims, but as you say it is simply not enough for the Press. Obviously the mainstream media wants Kerry to win, and will be reluctant to do anyting that hurts his chances so perhaps nothing would be enough. But I was thinking more along the lines of some of Kerry's 'band of brothers' turning on him, or if something from Kerry's unreleased records proved damning for him.
Witness Exhibit A, Serpenthead on the verge of blowing a gasket. The liberal commie elite media's MO is to vehemently attack the messenger ("Liar! You're a liar! I have no use for this guy!") while simultaneously ignoring the message. Perhaps they think the sheeple will listen to the louder voices screaming in hate rather than the calm voice of reason and experience. (And maybe they're right, in more cases than I care to think.)