pretty much the answer to this is "we are a big tent and a lot of people care intensely about things others don't care about at all"
strong economic liberals are always going to support people who come out hard against economic conservatives; strong social liberals are not going to support those people if they say (even in art, rather than as a personal endorsement) things that are hostile to socially disadvantaged groups. basically it's a question of what they will look past, and what vindicates an undesirable position/what we are willing to align with.
it's part of the fundamental conflict of the party--we are not sure what policy we want at the helm. sanders came across as paying lip service but lacking the chops (despite a history of marching alongside those fighting for black rights and voting in favor of VAWA/gay marriage/etc--because he was small potatoes until his economic stance put him center-stage).
imo it's also why healthcare reform was so hard for us. half our voters don't really give a shit about it.
an actually interesting perspective, thank you
do you think the fact that he was a (white) man running against a woman played a role in setting that narrative about Sanders? ---
He would make his mark, if not on this tree, then on that wall; if not with teeth and claws, then with penknife and razor.