> That you think it’s valid for the South to break away so they could continue to treat black people as property says a lot of things, none of them good.

They didn't actually say that, though I can see how one might read it that way.

  valid cases for secession. In the case of the South though

Is two things. I wrote a thing and an example, he's replied to both the thing and the example.

It's like Al Gore "I took the initiative in creating the Internet" being taken as "I invented" rather than "This was invented, I took the initiative in supporting it when that happened".