Nowhere in the Supremacy clause does it state that judicial decisions are supreme. Seccession WAS not illegal, the was no prohibition against it, the federal government has not been delegated the power to prohibit secession, either via legislation or by court judgements.
The TvW was a specious piece of bovine excrement, the holding that a Texas was still a state negated the decision on the bonds.
The supremecy clause makes the Constitution the supreme law of the land, trumping state constitutions and laws made under them when they conflict with the Constitution. And the Constitution gives the Supreme Court original jurisdiction over cases where states may be a party. The Supreme Court was well within its authority to rule on the Texas acts of secession and to determine if they conflicted with the Constitution. And that is what they did.
Seccession WAS not illegal...
Unilateral secession as practiced by the southern states most certainly was, as the Supreme Court ruled in 1869.
The TvW was a specious piece of bovine excrement, the holding that a Texas was still a state negated the decision on the bonds.
The Texas v White is a valid Supreme Court decision, your opinion to the contrary notwithstanting. And it remains as such unless overturned by a future court or invalidated by Constitutional amendment. Regardless of what you may think of it.