I don't think many would object if the discontented told the existing government that things weren't working out and some sort of separation would have to be arranged. Some might object, but a pacific, rational, moderate approach to separation would eventually have won out. But this wasn't the path the secessionists took. They felt themselves to be aggrieved and wanted to "act out" their anger. The saw themselves as the reincarnation of the revolutionary spirit of 1776. A false assumption, and one which encouraged them to take the wrong course.
Both sides wanted to win or keep as much as they could. Is this gangster behavior? I don't know. It looks more like the way states behave in the real world. Faced with threats or uncertainty governments assert themselves to ward off challengers.
What's irritating to some of us, is the way that some Rockwell libertarians portray government as a monster but make exceptions for the seceeding states or the Confederacy. They weren't lacking in those domineering and aggressive characteristics that are so objectionable in governments.
Unilateral secession will always be problematic because of the disagreement over the things the seceders can take with them. Of course the right of rebellion against tyranny exists. And those who favor separation are free to work peacefully towards that goal. But unilateral secession seems bound to produce wars, because each side will make itself the judge of the terms of separation.
Ex post facto legislation is unconstutional.
True, but I'm not really sure that term fits what Congress did in this case. Congress wasn't punishing anyone for things that were legal when they did them.
Their seeing themselves that way was an interpretation, a part of their world view, and as such may have led to misguided actions on their part. But interpretations do not have factual content and thus cannot be characterized as false. A quibble, perhaps, but I feel a need sometimes to state my objection to what I see as an gratuitous and inappropriate use of perjoratives, among which I would include your use of "over rationalistic".
I'd also like to make this clarification. As clear as it should be from my posts and explicit statements to this effect: I am a supporter of a very general right to unilateral right to secession and in particular in the case of the Confederacy in 1861. I am not by any means an apologist for the Confederacy in general or any particular personalities thereof. I hope you can understand this point; some (I won't mention names) seem unable to.