The Art of the Hissy Fit
The political cost to progressives and liberals for their inability to properly deal with this tactic is greater than they realize. Just as Newt Gingrich was not truly offended by Bill Clinton's behavior (which mirrored his own) neither were conservative congressmen and Rush Limbaugh truly upset by the Move On ad --- and everyone knew it, which was the point. It is a potent demonstration of pure power to force others to insincerely condemn or apologize for something, particularly when the person who is forcing it is also insincerely outraged. For a political party that suffers from a reputation for weakness, it is extremely damaging to be so publicly cowed over and over again. It separates them from their most ardent supporters and makes them appear guilty and unprincipled to the public at large.