The scenarios seem silly, since both side have the choice to ignore the other one.
The best form to avoid these situations is that the enviroment is after a while strongly controlled by big tribes (replacing what would be NPC control in other games). These tribes then will make the rules and griefing would in the end be what they deem as such.
The beginning will be like the wild west, and my wild guess is that even the devs dont really know how to deal with it if everybody wants to push their behaviour to the limits.