Having lived in the deep south, it's easy to see the paradox. Vehemently, deeply racist and judgmental people willing acting so selflessly at random occasions. Southern manners are usually just a facade masking hatred. I hate to say these things, but it is true.
“Southerns will hate the group but love the person. Northerners will love the group but hate the person”
Obviously that’s way oversimplified, but it’s broadly reflective of what I’ve seen. I’ve seen open casual racism in the South followed by kindness and empathy toward individual members of that race. I’ve seen public “performative” condemnation of racism in the North followed by quietly limiting the opportunity of individual members of that race by the very same people.
In my experience, Southern manners aren’t a “facade”. They’re the way people interact with the world. They do things out of a sense of duty, even - perhaps especially when doing it requires that they put aside their feelings about the matter.
We can talk Missouri in particular. Just a year or two ago there were anti-blm protests. I saw signs people were carrying with the n-word on them. This was in public and on television.
And I'm guessing this same person will use their southern manners accordingly when they come across a black person in their daily life.