Denial of a quorum, though childish, is a valid tactic.
On the rest, I don't think we are so much at odds as it initially appeared to be. The South made an appeal to rights which, not specified by the constitution, they retained (or so they believed, and reasonably so).
Lincoln's authority to invade, however, is a bit stickier subject.
In principle, it's a little worse than childish. As for this, I would make a few adjustments. I would say the slave states asserted a right they deemed to be in their own self interest, and based it as best as they could on republican principles. In my opinion, which is different from yours, I think they utterly fail to make their case, and are rightfully shunned by history. Back then, some of these folks made stuff up as they went along, run it up the flagpole, see who salutes it. Like Jefferson and his specious Kentucky Resolutions.