That’s not a dog-whistle, it’s an explicit fact. Nobody can win if their coalition is limited to white progressives. That’s who most of the Berners are at this point (although Ta-Nehesi Coates is a pretty interesting counterexample, but as a darling of white liberals he is an exception that proves the rule).
Frankly this sort of messenger-attacking is starting to become a signature pattern of the Bernie crowd. Disingenuous attacks are of course a fact of political life, but when you characterize every every mild criticism of your candidate as some nefarious smear campaign, not only do you miss the opportunity to counter that criticism, you come off as paranoid, fanatical, and out of touch with reality.
Blacks are quite capable of disliking someone because they are an asshole–someone who may be an equal-opportunity asshole.
Doesn’t apply to Bernie–who is not an asshole. They just don’t like him as much as some think they ought to.
(Thanks for explaining this “standard liberal” stuff to us!)
I definitely see a lot of paranoid rage among Bernheads, and a dismissal of every person or group who endorses Hillary as being hopelessly corrupt and in bed with the establishment. When that’s almost all Democratic senators, groups like HRC and AFL CIO and Planned Parenthood and the Congressional Black Caucus, when a lot of the same people had lionized these groups in the past, it starts to look isolating and like the people complaining are not really even Democrats any more.