Well, Terri, while I applaud Bernie for standing up for civil rights way back in 1963 before most voters were even born, he hadn’t bothered to maintain any type of relationship with the African-American community during his 25+ year congressional career. It’s not a safe assumption at all that blacks would automatically Feel the Bern because of a protest over fifty years ago.
Furthermore, African-Americans are church-loving people. I think it’s a very dubious assumption that a demographic of proud Christians would flock en masse behind a non-believer.
Also consider that President Obama is nearly unanimously beloved by black folks, so Bernie’s pointed criticisms of the Obama administration would not play well with them.
These same points also hold true for all non-whites, so it’s naive to take for granted such a huge contingent of voters. I’m not saying Bernie couldn’t mobilize people of color if he were the nominee, but it’s questionable how he would do it.