Nicely stated. I tend to agree with this logic.
I'm not sure if I believe that any Democratic campaign is willing to go this hard against black voters. In this instance,though, there is a desperation, and they probably don't see it as very likely that they will be able to win the black vote anyway in the primaries.
Clinton has very little left to lose of the black vote. It's actually been that way for a while (since before SC). That's why polarizing the contest along racial lines is a good (vote wise, not morals wise) strategy for Clinton. Whether Clinton has consciously pursued that strategy or not, I'm sure we all have our own opinions.
It's not good for Clinton since it renders her unelectable in the GE. The only thing she's done is destroy her and Bill's legacy.