

Just my assumption, but their party preys pretty heavily on the lower class. The lower class not having easy and cheap access to birth control makes it easier to produce more lower class.
They don’t care about having as many babies as possible. They care about generating more voters.
Also worth noting, segregation may have “ended” in 64, but there’s still soft segregation to this day. There’s a massive divide in culture, that’s left over from administrations such as Reagan. Racism still hasn’t ended, although it has gotten a lot better just in the time I’ve been alive.