You didn’t specifically make that argument, however the position of the southern slave holders which you defend leads directly to that question. The slave holders claimed that the slaves were their property and they could move their property around to suit themselves. That was the crux of the argument about the admission of new states to the union. If they weren’t slave states then the south could see its political leverage, control of the senate, being lost. This led directly to the Missouri Compromise which preserved the political balance by admitting Maine and Missouri at the same time. However, that was only a stopgap and the question would surely have arisen if a southern slave holder wanted to take his slaves to California to raise cotton in Kern County.
I simply can’t see a defensible argument for the slave holders in insisting that since Lincoln and others wouldn’t consent to the perpetuation of the institution of slavery in the US then secession was justified. It cannot be claimed that today’s mores are being imposed back to a time when they don’t apply. Slavery had been largely abolished in Europe by the early 1800’s and the US practice was in accord only with with repressive regimes such as Tsarist Russia. This was known to the framers of the Constitution and they ducked the issue in order to get some sort of effective government to replace the Articles of Confederation. Even the Tsar abolished slavery in 1861, and without bloodshed.
A legalistic defense of secession on the grounds that the south was only trying to enforce the constitution won’t wash. They were trying to get the constitution to uphold an odious institution in spite of clear words in it that guaranteed liberty to Americans and was established for the purpose of “promoting the general welfare and … securing the blessings of liberty …”