Hey, if Mandos had to have a civil war, which type of Mando would be the "good" side and which would be the "bad" side ?
I don't think you could label a mando civil war in terms of good or bad.
You would really just need two leaders with differing points of view and enough charisma to gain followers.
Good and bad are point of view. Death Watch views themselves as returning their culture to 'glory'. So they feel that they are the 'good guys'.
These terms, like history, are made by those who are left standing when the war is over.
Those who would be in the crusaders (whatever your reason) could do so with moral impunity. Since many of the armies at the time were conscripts pressed into service.
You could have your own reasons to fight without agreeing with those of your leaders.
How long you could live with what you must do during war time is all on you.