It's worse than that. If someone "thinks" you dissed him, whether you objectively did or not, they you can't defend yourself when he attacks you for the imagined "dis".
True, and the mere hint of an accusation by one of the tribe carries the weight of law.
Pre-emptive self defense requires that if you think that he thinks you dissed him, you must attack and disable him before it becomes necessary to ward off an assault.