You mentioned that in ASOS, the Karstark military were ordered to desert before the murder took place. My question is, why would they follow this order as a whole, or even in the majority? As bandits they seem to be in a far more dangerous situation than as part of an army, half a continent from their home and with little prospect of returning home to their families. Even with the promise, I would imagine those men would try to return to Robb’s camp once news of the execution began to spread.