What proves you point is all of the treason trials and executions there were post Civil War. Oh, wait there were no treason trials during reconstruction, never mind.
The choice not to try the leaders of the Confederacy after the was was primarily political, and was conditioned upon their signing new pledges of allegiance to the U.S.
The old South should venerate Lincoln, since he was the one who laid the groundwork for reconciliation, rather than the legal retribution desired by the
radical reconstructionists.
Jefferson Davis and El Kabong1 are in agreement on the issue of treason trials. Davis wanted to be tried for treason so he could use the trial to argue his case, but the Yankees chickened out and never brought him to trial.