I've looked through my entire copy (reprint) of the 1864 Index of Military and Naval Laws of the Confederate States, and nowhere do I find the terms "traitor" or "treason" used in any section dealing with the officers or soldiers of the U.S. Colored Troops. In fact, the only crime mentioned in those sections is incitement of servile insurrection. While I can't deny that racism must have played a role in Southern attitudes towards colored soldiers, I think that fear -- fear that the slaves might be incited to bloody revolt -- played a far more important role, and that's the reason why incitement of servile war was the only crime mentioned.
Finally, it was David Upton, I think, who made the point that the burial of soldiers on the field of battle, even when done in haste and en masse, does not dishonor those soldiers. If they were to purposely leave the bodies where they lay, to decay and be subjected to the tender mercies of wild hogs and other animals, that could be considered as dishonoring the dead. Certainly soldiers would not dishonor their own dead, yet there are photographs and written descriptions of Union soldiers buried at Cold Harbor who were interred in expedient graves so shallow that a year later their remains were exposed. So one should not automatically assume that Confederate dead buried in a like manner were somehow being dishonored.