There have been similar cultures throughout history and throughout the world. Many Native American or Pacific Islander tribes refused to take up arms. Those tribes are no longer with us, but the cultural idea that one should not inflict violence on your fellow humans keeps popping up.
I think the paradox results from a confusion of static vs. dynamic equilibrium. The consequence of not fighting back when attacked is that you end up dead. But that doesn't mean everyone will fight back - people end up dead all the time, there are plenty of human behaviors that lead to the death of their host and still persist (suicide being the most obvious one). Empathy is pretty deeply rooted in the human psyche, and is adaptive under most peaceful conditions. It's not a stretch to imagine groups for whom it becomes a way of life, at least until they're dead.
I think the paradox results from a confusion of static vs. dynamic equilibrium. The consequence of not fighting back when attacked is that you end up dead. But that doesn't mean everyone will fight back - people end up dead all the time, there are plenty of human behaviors that lead to the death of their host and still persist (suicide being the most obvious one). Empathy is pretty deeply rooted in the human psyche, and is adaptive under most peaceful conditions. It's not a stretch to imagine groups for whom it becomes a way of life, at least until they're dead.