This seems to be the opposite of history. Until recently, violence was one of the only ways for any civilization to persist. The advent of nuclear weapons changed that somewhat (but not if civilizations begin to use them). And most of the myths of a civilization seem to be a byproduct of their actions.
Being warlike enough to defend your society is one thing; being warlike enough to conquer neighbors who hate you, or to throw away lives and wealth in pursuit of glory, is something else. Sparta, Assyria, and the Aztec Empire didn't turn out so well, after all...
By that standard, we have extremely few dynasties who could be called "successful" these days. But I do agree that transitioning from very warlike to just somewhat warlike tends to help survival.
They fell well before the Macedonians, too: a commander of a minor city -- Corinth, I think -- noticed that the Spartans always used the exact same tactics, deployed his troops in a preposterous formation that ensured that the Spartans would lose if they changed nothing, and won decisively. The Helots immediately revolted and recovered their independence, and that was the end of Sparta.
Yet an argument based on Darwinism that we can't fight extinctions by compensating for maladaptation is so blindingly obvious ... Compensating for maladapted species will need an amount of resources that evolves exponentially over time, even if the numbers of the "saved" species don't increase. Therefore it will fail, it is only a question of time.
Atheists at least see that particular myths are utilitarian. To make a society work and produce, for instance. Or to make a society fight, like some other religions. But they fail to look in the mirror and see that their myths are utilitarian as well, and when they are true, that's not a great factor in their adoption. Belief systems are like computer viruses : correctness, correct use of the system, style of the code doesn't matter (in fact it is often an obstacle). What matters is whether the code spreads.
And just like atheist myths can be true, religious myths can be true. The bible contains quite a bit of true history, and I would argue at least a bit of good advice. It also contains lots of instructions for various things, from architecture to agriculture, and those instructions work, even if they can be said to not be perfectly optimal. Likewise, you can make an argument that the quran contains instructions for warfare that are certainly not stupid, even if some of those tactics make "realpolitik" look like two girls trying to feed bambi.
Of course the above is the non-cynical view of their position. The cynical view would be that conservation is not in fact done to help species, but rather to increase the luxuries surrounding rich conservationists. That conservation efforts are just a very expensive 50" tv, and the beneficiaries of conservation efforts will be chucked in the bin when something else catches our fancy just like said tv.
I didn't get that from the article. The author seems to have looked at how people justify violence and found they gave moral explanations. Whether their morality is relative or absolute doesn't seem that important to the argument.