It's more like, in the heat of the moment when given only split seconds to make a decision, all of this intellectual nonsense being spouted....won't even occur. They'll make a decision based on pure instinctual gut feelings, and only consider the consequences of such a choice once the situation is over and the adrenaline has stopped pumping.
@Generic.Archdemon is talking a load of bullshit. You wouldn't have time to make all of these considerations when given only seconds to respond. Simplify your meandering to:
1) No, because it doesn't concern me or benefit me enough somehow.
2) No because I'm against tribalistic violence regardless of my association with said loved one
3) Yes because I'm loyal to person enough to disregard the reason until the situation is resolved, meaning I can now ask questions
4) Yes, because fuck the other guys faction anyway