What Mrs. Merriweather is talking about here is people up in the North. She is blaing them for setting the slaves free after the Civil War.
Of course, I would never say that setting the slaves free was a bad thing. So in that sense, no, she does not have a point.
What she does have a point about is that people in the North did not have to live with blacks and therefore were able to feel really superior to the Southerners. Most Northern whites believed in white supremacy too, but they did not have blacks around them so they could just look down on the Southerners for how they acted.
You can sort of see an example of this in how the North supported the Civil Rights Movement but then MLK got hit in the head with a rock when he tried to help integrate the Chicago area.