Ah, but there's already rules in place that weren't followed, and even if there weren't, when a goal is stated, and someone undermines that goal, you can still address that conflict, even if you didn't spell out rules, which are no more necessary to address they goal than they are to know how to screw things up for lulz.
There's not really a way around it. Someone has done something highly organized to screw up someone else's work. The entirety of the blame for that lies on the person who intentionally did such a thing, not on those who have a great system and community working towards a goal for not anticipating the worst.
I'm the last person to use the word "victim blaming" but if I leave my door unlocked and you come take my TV, "he should have known better than to leave his door unlocked" is not a defense, it's an admission of guilt.