Isaac thinks John Weaver's quote is the most damaging part of the NYT's McCain story. Jamie thinks Weaver isn't credible since he's presumably disgruntled that McCain "fired" him. I think Isaac has it more right than Jamie.
First, Weaver wasn't fired, he resigned after losing an internal power struggle to Rick Davis, who became McCain's campaign manager. (GQ has the best account I've read of the McCain campaign's summer '07 unraveling if you want the details.) Second, even though Weaver was obviously hurt and angry when he left the McCain campaign, he's still a total McCain loyalist. "[I]nformal campaign adviser" is not, as Jamie alleges, a "puffed-up euphemism for 'unemployed.'" As I reported a few weeks back, Weaver continues to offer advice to McCain through various back-channels and there's some talk among McCain folks that he could officially rejoin the campaign for the general election battle. All of which is to say that the fact Weaver told the Times about confronting Iseman at Union Station is significant.
So the big question is, why did Weaver talk? My hunch is he had no choice. I assume the Times got wind of the Weaver-Iseman showdown from other sources and confronted Weaver with the information. He confirmed the info and then put as positive a spin on it as he could--which, if you parse what he's saying, seems to be: this woman was running around saying all sorts of damaging stuff about her relationship with McCain, and we didn't think what she was saying was true, so we told her to cut it out. Now, whether Weaver is to be believed on this is another discussion; but the idea that he's trying to hurt McCain--rather than help him here--sounds wrong to me.
Update: I see Crowley did a post with some similar thoughts--including reaction to the story from Weaver that bears out much of what I wrote above.