G.W.Warthan ended the war in a POW camp in Columbus , Ohio as a result of a rear guard action after the Franklin , Tn battle with what was left of the 32nd Texas Cavlary.
He was one of the last 65 to be let go out of this prision because he kept refusing to sign the oath.
The family story goes he was convinced by the last ones in camp to sign but as a matter of conviction and rebellion, the practice was to sign with an "X".
I have a his release records from the US that has the X.
There are probably as many reasons and logic as to the importance of the oath as there are people.