The only people who had read and cared about the constitution lived south of the Mason-Dixon line? Yeah, right.
If it was all simply a giant vindication of the constitution and the will of the founding fathers, why didn't free states join the south's holy crusade? Why didn't the slave states send commissioners to each of the free states to try to persuade them to join in the south's experiment in the ulimate exercise of the theory of state's rights? The answer: they weren't slave states.