it's a fair to point out that those segregationist democrats would probably not be democrats today (with the exception of Robert Byrd, RIP) but there is another institutionalized racism (though not as overt) posed by TODAY's democrats and that is the racism of lowered expectations and patricianism (they're not sub-human, but they're children that need us to look after them). I'm talking about white liberals of course. And look at the reaction from the left when one of their wards goes "off plantation" and the Uncle Tom epithets fly.
I think it's fair to point out that that dynamic exists, but to what extent? I don't see it at all as the core of liberal thought or action on the matter. I think it overlooks the much broader goal to genuinely aid virtually an entire race that had, from our founding, only participated in the "american experience" as chattel, or at best disenfranchised undesirables. The rest of us had at least a couple of hundred years head start on them in terms of being "created equal". Did anyone really expect the black man to suddenly go from subhuman status to being welcomed into and flourishing in mainstream america? I know Abraham Lincoln didn't.
100 years after being freed these same people were still being systematically and societally oppressed. So yeah, considering all of that, a boost, combined with empathy and patience, seemed to me like a logical, humane thing to attempt.
Where differences seem to arise is over how long that boost should last, and if instead it has turned into what you characterize it to be. Personally I don't think we've crossed over that divide yet - though we have at times erred in that direction. We're still only looking at two generations since the Civil Rights Acts passed. Hundreds of thousands of black americans are still alive who experienced the worst of institutionalized racism; who grew up under it - who had it impact their educations, employment opportunities, sense of actually BEING americans, etc etc. And it isn't like racism just up and vanished based on changes in the law. Though clearly not as prevalent, it's still alive and cooking.
PS: Why (were he alive) include Byrd among current segregationists? He had his epiphany in that regard decades before his death.