I do not see why a seditious and treasonous general is a problem. About a third of my best generals have the Disloyal trait and roughly half of them have the "venal", "seditious" or some other level of this trait. So far I had not encountered any problems, such as having those generals bribed, or anything like that. Unless you are playing VH on campaign difficulty, or when the AI goes bribe-happy, you will rarely see enemy factions bribe any of your armies or cities. What I have also noticed is that when a general is successful and wins a lot of battles, the seditious/treasonous trait goes away.

Are you doing the exile because you are afraid the AI will bribe them or is the exile strictly for roleplaying purposes?