Is their oath that each made to the United States upon commissioning or enlisting in the US Army/US Navy erased with their resignation or voluntary termination of service?
If it is, where does that leave those of us now who have retired/resigned from the military? Some of us .. most of us? .. believe that our oath still applies, even though we're no longer on active service.
If it does not, then a violation of that oath is something that must be faced. I'm reasonably sure that most, if not all, of the ex-US Army/US Navy officers and enlisted believed that the circumstances facing them required their "violation" of that oath, but, as such, they should be willing to face the consequences of that act in the event that their rebellion failed.
So, to me, that is the main question: what is the effect of their prior oath to the United States that they made when commissioned or enlisted in the US Army or US Navy?
All I can say is that I'm very happy that it's not something that I've had to face yet. If it reaches the stage where I have to consider that sustaining my oath is effectively violating it, it's not going to be an easy decision.