The main flaw in this argument is the assumption that governmental systems can or ought to be reduced to logic puzzles. The real world doesn't operate on a mathematical plane. The Constitution is only meaningful so long as sufficient members of the government and the citizenry accept it as an authority and share a somewhat similar understanding of its implications.
If the government goes off track from the Constitution with the willingness of the populace there's nothing in the Constitution or the world that can stop it.
Consider the birth of the Constitution itself: there was no mandate for an entirely new baseline document to replace the Articles of Confederation. But one was created and the states adopted it. It came into power because the citizens of the United States gave it power. That's the only way governments are formed and changed. The founders of the US understood that very well.
If the government goes off track from the Constitution with the willingness of the populace there's nothing in the Constitution or the world that can stop it.
Consider the birth of the Constitution itself: there was no mandate for an entirely new baseline document to replace the Articles of Confederation. But one was created and the states adopted it. It came into power because the citizens of the United States gave it power. That's the only way governments are formed and changed. The founders of the US understood that very well.