If a person abandons their US citizenship, it's done by the person. If that person then claims citizenship in another country that's never been recognized by the US or any significant country in the world, that's on the person.
Poor sap, he loses all the constitutional rights he had in his former country, then in a few years his new country doesn't exist so he's left without the constitutional rights of any country.
Are you kidding when you said J. Davis was denied his constitutional rights? He had none from his former country or his thoroughly-defeated dalliance of a new country. Poor sap. Poor treasonous, pro-slave, live-off-the-sweat-of-other men's-labor sap. Stupidly selfish cause and stupidly selfish leader.
Do you actually not know what the Confederacy was founded on, by their own documents?
How justified it is that J. Davis lived out the rest of his life in pathetic status, a small price to pay compared to that needless death of thousands called the Civil War.