I disagree. Scientists do harm to the atheist movement in the longterm because their métier is not metaphysics (aka philosophical bullshit). What we need are skilled orators in the vein of Hitchens with firm grounding in history and contemporary politics. Hitchens', admittedly non-scholarly knowledge of islam trumps that of Dawkins and Krauss.
Well, I partly agree. Partly because their aren't too many public speakers who will spoil you with the oratory magnificence of Hitchens. I also wouldn't say that scientists do "harm" to the atheist movement, because they represent the frontier with which we've rendered religious creationism false, the scientific frontier. They are central to the debate.
But yeah, there are few things more embarrassing than a scientists lost in the landscapes of philosophy, history and contemporary politics. Not only that, but most scientists are exceptionally pale and dull in their presentations as well. Neill Degrasse Tyson, you are of coursed exempt.