But that's not what you were implying. By your quotes you were trying to imply that the trial of Davis didn't proceed because he couldn't have been convicted because secession wasn't illegal. Any such acquittal would have done no such thing. The question of the constitutionality of the southern acts of unilateral secession was settled separately in Texas v. White. And the justice that wrote the majority opinion in that case was the same Chief Justice Chase who would have sat in judgement at a Davis trial.
It's not an implication. The yankee lawyers wanted no part of this case because secession would have been found to be legal and Davis would have been acquitted.
A nolle prosequi was entered in his case and his disgraced enemies set him free.