As mentioned already, the course you would take would be dictated by what ALL of the Players think of this situation. Are they po'd at each other?, wanting to kill off their characters? etc.
Sounds like the death penalty is already a done deal though...
If the GM wanted to change his mind he could say General X was just scaring him. A shuttle comes by and picks him up off of the death planet after a couple nights. Or General X pulls them to the side and tells them they can redeem themselves if they accept a secret mission. There is an unknown mole amongst the Rebel cell. The sentenced player(s) have the benefit of being believed dead, so....
I'm in the anti-death penalty group. The Alliance are the good guys. When was the last time the US military executed someone for cowardice under fire?
Why not just use Contribution Rank? Knock them back to Contribution Rank 0 or possibly 1 for the guy who wasn't punished as much. They are cannon fodder again with a bad name. They are going to be handed some crappy details. Then let them start to redeem themselves.
Edited by Sturn