If you say so, it must be true.
"Madison, in his letters, refers directly to the term secession and uses it to describe what would happen as each State ratified the Constitution, thereby seceding from (in preference to violating outright) the AoC."
< Please quote from Madison - one of my favorite patriots - and we can discuss what he meant.
"Sure it did. New contract, new deal, new government, new United States of America, new Union. Out with the old, in with the new.
Well, I'll ask you the same question I have asked another poster: What is the birthdate of the United States of America?
"The powers delegated by the proposed Constitution to the federal government, are few and defined. Those which are to remain in the State governments are numerous and indefinite. The former will be exercised principally on external objects, as war, peace, negotiation, and foreign commerce; with which last the power of taxation will, for the most part, be connected. The powers reserved to the several States will extend to all the objects which, in the ordinary course of affairs, concern the lives, liberties, and properties of the people, and the internal order, improvement, and prosperity of the State."
I have always enjoyed Madison's explanation of formation of the new government. What he describes herein, should be understood as the intent of the 10th Amendment. Unfortunately, the cabal forgets the last sentence, which even the most simple of simpletons can see provides no support for the idea of unilateral secession.
No doubt you have, at least as far as his quotes that seem to support your position are concerned. There are many problems with Madison though.
First and foremost, he was notoriously inconsistent over the years. He wavered from an agrarian jeffersonian to a centralizer to a jeffersonian again to a nullifyer to a centralizer to an agrarian again to an industrializer and so forth. For every quote he gave that seemingly frowns upon secession there is Virginia and Kentucky Resolution giving a substantially more favorable conceptual framework. Thus to rely exclusively or even heavily upon Madison as a determining authority in favor of a specified and defined position necessarily entails picking and choosing certain parts of Madison that mesh with the position you support while rejecting or ignoring those that don't.
Second, Madison was a reasonably intelligent man but in the generation of founders he was far from spectacular as far as intellectual capacities are concerned. This does not disqualify his position, but it does serve to explain why Madison was both notoriously inconsistent over the years and in constant pursuit of a better-refined argument. It also suggests that others may have seen and understood the forces at play in the founding era more clearly and with greater foresight than Madison did. Several specific founders who come to mind as having a substantially stronger intellect that Madison. Franklin is probably among them and Jefferson indisputably is by a long shot. Some of the most intellectually gifted founders also tend to be more obscure in today's popular histories, though not in importance to the era - men like John Taylor and St. George Tucker come to mind as some of the more intellectually gifted persons of that era. One of the most brilliant founders - and he was frighteningly brilliant at that - was Luther Martin. He was quick on his feet, rigidly logical, and had a commanding presence. Few if any other persons at the constitutional convention could best him in debate. His main flaw was that he was also extremely irritable and prone to being somewhat inflamatory. That said, he saw the future implications of the new government with greater clarity than almost every other founder to the point that he predicted the exact scenario of the Civil War almost three quarters of a century before it happened. My point in noting persons such as Jefferson, Martin, Taylor, and Tucker among others is to demonstrate that there are other sources out there with substantially more reliable and intellectually sophisticated takes upon the nature of the new government than Madison.