Sounds like Sir Arthur Keith is rueing the defeat of the Reich, to me. Let's look at the entirety of that passage, since we're speaking of omissions:
"The German Fuhrer, as I have consistently maintained, is an evolutionist; he has consciously sought to make the practice of Germany conform to the theory of evolution. He has failed, not because the theory of evolution is false, but because he has made three fatal blunders in its application. The first was in forcing the pace of evolution among his own people; he raised their warlike passions to such a heat that the only relief possible was that of aggressive war. His second mistake lay in his misconception of the evolutionary value of power. All that a sane evolutionist demands of power is that it should be sufficient to guarantee the security of a nation; more than that is an evolutionary abuse of power. When Hitler set out to conquer Europe, he had entered on that course which brought about the evolutionary destruction of Genghis Khan and his Mongol hordes (see Chapter 34). His third and greatest mistake was his failure to realize that such a monopoly of power meant insecurity for Britain, Russia, and America. His three great antagonists, although they do not preach the doctrine of evolution, are very consistent exponents of its tenets."
Looks to me like the full quote simply confirms the fact that Hitler's racist ideology was in great part founded in evolutionist theory.
It reminds me of the modern-day apologists for communism: They think that the Soviets just did it wrong.
Ummmm... He argues that Hitler was inspired by evolution, yet he also argues that he lost because his enemies - namely, us - were also inspired by evolution!
But hey - Darwin is responsible for Naziism, Darwin is responsible for communism, and Darwin is also responsible for capitalism. So why not blame Darwin for both sides of WWII?
I say Darwin was responsible for both the National League and the American League.