The obvious benefit this little story could give John McCain is that it might make conservatives like McCain more. After all, being attacked by the New York Times (read: elite liberal media) is a badge of honor for a Republican ...
But the other thing it could do is make him immune to future scandals.
When the "Rathergate" allegations about Bush's forged memos turned out to be bogus, it not only undermined the specific documents -- it actually negated all the stories about Bush's Air National Guard Service.
The point is; if this thinly sourced story is proven to be false, it might actually make McCain somewhat bullet-proof.