(1) It will simply call attention to a story that mainstream media is ignoring;
(2) It will make Brinkley look less like an objective historian and more like a Kerry flack;
(3) Serious reporters will squirm at this weird selective disclosure - the January after-action reports are not at Kerry's website, but Brinkley can miraculously rely on after-action reports and Kerry's own War Notes to present Kerry's story? Someone in the press may rebel and ask for both the already-promised after-action reports and access to Kerry's notes (ask for December and March 18/19 after-action reports, while you are at it. And the paperwork for the controversial first Purple Heart).
(4) Brinkley will not have a good explanation for his decison to leave it out of the book in the first place. Possible explanations, none appealing - (a) Running covert operatives to Cambodia makes John Kerry look like a macho man of mystery and danger, and that was not the picture Brinkley wanted to paint; (b) Brinkley didn't want to suggest that Kerry was involved in Nixon's secret war, or that Kerry broke international law by violating Cambodia's border (except when he did); (c) it doesn't square well with Kerry's own account of his March 18 mission near Cambodia, as excerpted in Brinkley's book, where Kerry made it clear that violating the Cambodian border was a Big Deal.
The campaign will conclude that it is safer to let this drift away. Well, that's my guess. I hope I'm wrong.
MORE: OK, this is brutal, but how big is the San Francisco Examiner?
UPDATE: Props to the Captain - evidently, "served under Kerry" is a slippery concept. MORE: Oops! Read the comments! The Captain has good evidence that Alston left, but no real evidence that he did not return. Lots of good research being done by Lori from Texas, however. I'd love to get her to compare the Feb 20 action described at Kerry's website (which seems to blame the helicopters for wanton destruction) with the Feb 20 after-action report. (Actually, that would just be a warm-up...)