The gist of many secession-defenders, like you, is that the north didn’t care about slavery only using it as a pretext to use freed slaves to fight for them. Then answer me, why didn’t the north allow slavery to be reinstituted at war’s end, huh? Stop the evasive answers and answer that one simple question.
As I've stated repeatedly, in writing, the critical issue is the constitutionality of State secession - not slavery. If State secession was constitutional, then it would not have mattered if the Southern States seceded to preserve slavery, or donate tax proceeds to the Little Sisters of the Poor - the federal government would not have been justified in opposing it. The most important common issue in the 1830s and the 1860s was the constitutionality of secession, not slavery:
...the people of this State will thenceforth hold themselves absolved from all further obligation to maintain or preserve their political connexion with the people of the other States, and will forthwith proceed to organize a separate Government, and do all other acts and things which sovereign and independent States may of right to do.
- South Carolina Ordinance of Nullification, November 24 1832
Others here prefer to focus on slavery, no doubt because it supposedly lends moral authority to what are by definition legal arguments. In short, I would suggest that your summary in post #921 should be revised: States' rights before the war, no States rights after.