It should be pretty clear what he's doing here, or what he was told to do. Harry Reid got in some trouble a few years ago for saying Obama didn't use a "Negro dialect" and didn't receive much of any pushback from the media or democrats. The GOP has decided attacking Reid is an allegedly good way to build base momentum. The inevitable denouncements that occur now will spur Bundy, Fox, and republicans to point out no such outrage occurred on the left when Reid used the same word.
Nevermind that Bundy went overboard into blatant racial rhetoric; the problem isn't saying "Negro" it's what comes afterwards. If we had a decent media it would be very easy to step over this trap and simply ask Bundey supporters if they believe blacks are better off now than they were as slaves. Yes or no question.
I guarantee you Fox, right wing media, and certain GAF posters will bring up Reid today.