But I Voted for Shirley Chisholm

Obviously I disapprove of this sign. And as I've said before, I don't think opportunistically quoting Shirley Chisholm or factoring out actual human beings to determine their precise privilege quotient is particularly clarifying.
With that said, as with Elizabeth Cady Stanton and Susan B. Anthony, it's always good to understand the roots of the angst. For my part, watching a major presidential candidate who's been accused of sexual harassment multiple times, crack Anita Hill jokes, deride the first woman to rise to Speaker of the House as "Princess Nancy," and finish the week by warning other accusers to "think twice," clarifies that particular frustration.
That the frustration is sometimes poorly -- even erroneously -- articulated or given voice by white populists should be duly noted in the starkest terms. But the anger comes from somewhere. I simply have a hard time imagining, in similar context, a presidential candidate berating Obama in such overtly racist tones. "Food stamp president" and flirting with birtherism are pretty close. But there's at least some plausible deniability.