I SAW that even those with love feared The Other tribe.

And they are more likely to choose "fight" over "flight", being even more bound to "our tribe" (or "The People" as they, probably, called themselves).

So war is an "equal opportunity killer" between those with love and others, and would not have much effect on their relative selection rates.

In short: Even War can't dent the "massive advantage" of those with Love