they have no right to self determination within their geographical political block?
Of course, but within the limits set by the federal government. If CO decides to buck the power structure and legalize marijuana, the Federal government could use their authority to put the state back in line. And that's just one little difference in drug policy. You're talking about a whole section of the US completely refusing to comply with the Federal government.
That is who was being oppressed. Does have to be an ethnic or religious group? No. Doesn't even have to be any oppression. Just the desire to self-rule. Why don't you answer the question I asked about the Constitution prior to 1861? Why? Because there isn't anything in the Constitution that makes secession illegal prior to 1861.
What he said. I have can offer no moral justification from preventing anyone from seceding.
There's no moral justification, just a realist one. National security and stability ahead of liberty and self-determination. I don't even think the realist justification is strong looking at similar examples in other parts of the world.