Rush said it was true and that McCain took a long time to turn him down.
That would be the salient fact.
Kerry could have asked Duncan Hunter, Oprah, the Easter Bunny, (would explaing the blue bunny suit ;_)) Obama, and a host of others.
What matters is not who was asked, but whether they fell down pointing and laughing; looked puzzled, and said, "Hell NO!"; or said, "I'll give that serious consideration,"...and did.