Abraham Lincoln was not holy and in this case was afu legally.
There is no Constitutional requirement to relinquish a right to reconsideration of union, Especially by states subsequient to the original thirteen.
As a matter of fact there was a situation of some NE states possibly deciding to leave the Union in the early 18teens, this when many original framers were still alive. It was not addressed Constitutionally as it wasn’t even considered relavent, (”Have youse lost your minds,we just said and died to claim our God given right to self determination?)
true today as well re: the totally sovereign Republic of
Texas joining agreement IN ABSENCE OF CLEARLY SPECIFIED indications is VOID of such requirements.
“Now youse can’t leave.”