Dave Weigel is an outstanding progressive writer, but I really disagree with the premise of this statement:
It's just that they should know that calling out a group for "racism" is pointless -- whoever's been targeted will simply claim to have been attacked unfairly and had his free speech threatened. Remember what happened when Eric Holder said that America had been a "nation of cowards" in discussing race. Boom: Backlash. Anger. Debate over why he said it, but not what he meant.
Unless I'm misunderstanding his point, it appears as though he's saying we should avoid a fight whenever there's the possibility of a stupid backlash. This is old school Democratic thinking. We need to be perpetually vigilant about calling out the crazies, racists and liars, because as soon as we ignore them (especially for the sake of avoiding a thing) they continue to entrench. These people have to be marginalized, regardless of how much they screech when they're attacked, and the only way to achieve that is fact-based, reality-based political tenacity.