Yeah, I think that's a fair assessment of the situation.
The Southern slave states basically had two complaints: tariffs, which were in place to foster growth of American industries and to raise revenue for the Federal government, but cost Southern agricultural businesses more money, since they had to pay most of those tariffs; and the Southen states concern that eventually slavery might be outlawed.
Now rather than say that they didn't want to pay taxes on imports, and they wanted to continue to own human beings as slaves, their apologists latched onto a euphemism which makes their treasonous war against the Republic sound more noble and less venal.
We're weren't fighting for our right to exploit people as slaves, and so we don't have to pay taxes on imports! NOOOOOOOOOOOO, we were fighting for States' rights.
Of course, take away the issue of slavery and our forefathers' rebellion would have never happened, and we all know that perfectly well,
So let's just all pretend that we were fighting over some noble sounding principle in the law, because describing our REAL motives makes the myth of the chivalrous South look rather like the great big fat lie it really was.