You want to argue that murdering totalitarian communists weren't influenced by Darwin, I'm sure the Lord will hear you out.
I'm sure he knows totalitarian murderers will rationalize their actions by twisting whatever source they can, whether it's a science book or the Bible.
More depth: You can't logically use the theory of evolution to justify suppressing or killing others because "you can't get from 'is' to 'ought.'"
This idea was developed by David Hume. He noticed that people often made a leap in reasoning where they would start by describing the way things are and then suddenly start saying because of this things ought to work in such a manner with no justification. So we can say that without outside help those who are weaker or less intelligent are less likely to survive than those who are strong and smart. However, leaping from this to saying that therefore we ought to either not help the weaker or kill them is a logical fallacy.
Anti-evolutionists continually say that without God there can be no morality and anarchy would reign. However, many agnostic evolutionists realize that the way nature works is often brutal and arbitrary and see no reason why we should be complicit with it.
Our idea of fairness and justice arose as self-preservation method--an emotional response to another being wronging us can discourage the other from doing that again and can encourage us to distrust that other. Cooperation arose as a form of kinship selection and then acquired usefulness in the larger group due to its mutually beneficial nature. So evolutionarily we are equipped with the ability to know when we are being wronged and to feel guilty when we wrong another, but we are also equipped with the tendency to limit moral dealings to those in our group.
We know we are inclined to limit cooperation and moral dealings to those of our group (our nation, race, religion, etc.) We also know that we are all humans and that there is no logical reason that our particular interests or desires should triumph over those of another. So our innate emotional responses can couple with logic to give a morality that is the essence of the golden rule--Do unto others as you would have done to you.