This kind of thing isn't new and will continue to happen. After being an integral part of the civil rights movement, groups like the NAACP have to seek to keep themselves relevant and will end up taking aim at the wrong targets. Frequently such action will backfire and embarrass the organisation itself.
I'm not American, but I would hazard a guess that away from the mainstream and the
PR disasters like this, the organisation still does some worthwhile and important things. Judging by some of the comments in this thread, its existence is still justified.