I don't know whether he said it to someone. It has been publicly reported and not denied. Until it is at least denied, the presumption rests with the story.
Wrong. Any such statement by a lead United States diplomat working in the powder keg of the Middle East would be serious, serious news. And it is the job of the journalist to provide confirmation, not the job of the subject of the story to deny every allegation levelled at them.
I simply haven't seen any other mention of it. It's like the Sherlock Holmes tale, of the dog that didn't bark. That fact that the pro-Palestian segments of the press aren't baying for Zinni's head speaks volumes here...