In both cases, I think I agree with them. Per slaves, the amendment needed to be implemented, and per secession, well, might made right. The north banged them into submission, and the issue was settled.
Well, yep. I mean, they had a right to attempt a different interpretation of the Constitution.
What makes this really interesting is per James Oakes, “Freedom National,” the abolitionists in the 1830s developed a long-run strategy to end slavery either democratically by bringing in so many free states via the territory system they would have the votes in Congress or via amendment to remove it, or, by military force if the South reacted with a war. This is a brilliant insight as Oakes supports this with numerous SOUTHERNERS who saw exactly the same thing, and warned that if war came, they would lose their slaves.