They can fight for self-defense. But 'fighting' (whcih is what you people said you don't want to do) comes at a cost. And any soldier will tell you, that taking another human life, be it in justified self-defense or not, changes you.

also the alignment system that is on the current totem will play into that, so if your a good tribe and you pk then you will get kicked from your own tribe if you kill to many people.
I left this seperate from good and evil alignments. Maybe these could be tied together. However, I don't agree that PKing in and of itself is an act of evil necessarily. As Jadz said (a militant) can justly defend themselves through violence. Which is not an evil thing. A pacifist simply doesn't believe in solving their problems (even when attacked) through violence.