Complete nonsense. Davis had about as much of a chance of walking as did those swept up in the Lincoln assassination conspiracy.
Well, it seems some well known historians and jurists DISAGREE with you. Nolu Chan is right. The proof could be in front of your face, and you wouldn't believe it.
The only conspirator tried before a civilian jury, John H. Surratt, tried in Washingdon, D.C., WALKED.
100% of those tried before an Article III court WALKED.
Apparently, Davis had a 100% chance of WALKING.