The brillant thing (or one of them) about the Constitution is that it takes human frailty into account.
What you CSA apolgists posit is some impossible nirvana where everyone can act like small children without any consequence.
The Constitution MUST be interpreted and implemented by men. You seem to discount that. Some person or group of people MUST have the final say. And the Supreme Court ruled that the Militia Act, among other things, gave the power to the government to resist insurrection. The fact that the law was originally passed to put down a small insurection in one state doesn't change the words.
Really, the slave holders should have read the Constitution and the laws a bit more carefully and they wouldn't have had their applecarts upset so badly.
Walt
First, point out ONE law forbidding secession. There isn't one. Secondly, why would they think anything else. The military leaders had been taught secession was legal at West Point, the political leaders had followed in the footsteps of northerners like Timothy Pickering, George Cabot, and Alexander Hamiliton all of who called for secession on more than one occasion. None of those men were called down for their thinking and even had the backing more than once to go through with it. But for the fortuitous ending of the War of 1812, they would have.
So before you start down this road AGAIN look at the history of the men who came BEFORE lincoln in the north