He did.
When it came out that not only had McCain peddled this "dossier" to his Obama contacts at the FBI, but had sent a personal aid on a plane over the Atlantic to personally retrieve a hard copy of it in Europe, McCain immediately knew he had been exposed, and went into damage control.
Using his media skills of appearing on Sunday news programs hundreds of times, he knew he had to the negative information "out there" before he as immersed in scandal himself. He also knew the media would be friendly to him. So he threw out some wild lines about how what a "good citizen" he was and that peddling this crap was something "any loyal citizen would do."