I recall reading a review on "Tour of Duty". It remarked that all of Kerry's crewmen were interviewed and quoted in the book -- save one.
That would be Steve Gardner. His absence was explained away by his "conservative politics". Brinkley evidently contacted him, but it wasn't clear whether Brinkley decided against using Gardner's comments (because they were undoubtedly negative) or because Gardner declined to be interviewed.
I'm not sure Brinkley interviewed any of Kerry's commanders -- on the Gridley or in the Swift divisions.
Accordingly, Brinkley didn't so much provide a biography of John F. Kerry, but a "Reminiscences of..."
But see, that's a big point: contacting the guys on KERRY'S boat does not equal talking to the guys who were THERE---within 5 feet of Kerry. It would be like talking to one guy in one militia unit on Bunker Hill but not another guy 4 feet away because he is not in the same "unit."