I don't mean to take anything away from Ari, far from it. However, those bald faced lies McCain's been tossing around in a matter-of-fact kind of way is painfully impossible to defend against, and I certainly wouldn't want to be put in the embarassing position of defending those blatant lies against the obvious facts of the matter.
Ari's job as the defender of truth is so much easier than Brad's in the OP's second link, where Brad had to cook up more lies on-the-fly to defend McCain's lies, whereas all Ari had to do was be honest.
I haven't the slightest idea why McCain believes that lying like he does will get him into the Oval Office...Well, on second thought, it worked for Bush twice so I guess there is a precedent for it.