Again,,, it’s an interesting and humorous concept that the Supreme court says it’s illegal to seceed. Imagine the USA truly elected a marxist and became a socialist dictatorship. And that a state decided that the time to end their association had come, but that this SAME state still thought they must abide by supreme court rulings. Odd.
This reminds me of thinking you can stop a mass shooting incident in the mall, by posting signs that guns are priohibited on the premises.
One would have to assume that a socialist dictatorship would have done away with the Supreme Court when it did away with the rest of the Constitution, so your point is somewhat moot.
If we had a Marxist dictatorship, the Constitution would be by very definition trashed. Even if there were an enumerated or implicit right to unilateral secession in the Constitution, (which there isn't) the dictatorship would ignore that and attempt to impose their will.
That is when the people revert to their God-given Right to Revolution under Natural Law.
If Texas decides to go... 9 robed jurists will have NO SAY.