We can debate the legality of rebellion and secession till the cows come home; it doesn’t affect the legitimacy of the 14th Amendment as written.
The Union made state legislative ratification of the 13th, 14th and 15th Amendments a precondition of their resumption of federal representation so that those representatives could not later disown those Amendments and reopen the issues the war had settled.
Like I said: a hard bargain; but when you bet everything on black and the house wins, you’re bargaining position has pretty much Gone with the Wind.
That’s “your bargaining position,” of course.
***...reopen the issues the war had settled.***
The death of States’ Rights and the end of the principle that this nation was literally founded upon.
MamaTexan does a pretty good job in post 79 as far as the legitimacy of the 14th. And might I add 2 Northern States rescinded their votes, though this was a minor inconvenience for Congress, to be dealt with by pretending it didn’t happen.