So they actually tend to over-focus on Darwin and the minutia of his various beliefs...much more so than actual evolutionists today. They assume that evolution, like creationism, is simply based on one old (but not nearly as old) book that they imagine is taught in schools and universities like some sort of religion or received wisdom. REAL evolutionists are too busy running around observing animals and digging up and dating thousands of fossils and putting together clear and obvious sequences of transitional fossils to spend all of their time examing Darwin. Darwin is respected, of course, for the original idea, but the science has moved on. Evolution is now based on immense stacks of fossils and data from the field, not Darwin..it's not "fossilized" like Creationism.
Thus, looking at Darwin's personal morality, philososphy, political beliefs is completely and utterly irrelevant to the evolution debate. He had an idea about evolution which has since been supported by the work of thousands of biologists, paleontologists, etc. in the field.
If Darwin had advocated raping and strangling all babies, or if it is discovered that Darwin's secret hobby was raping and strangling babies, it means Darwin was an evil sicko but doesn't mean jack squat for evolution or that the evidence for evolution is any less clear-cut.
The article establishes that Darwinism leads to Social Darwinism. Did you read it?
Were I to criticize the article, I would fault its equating natural selection with evolution. Natural selection is simply the environmental context while evolution is the mechanism(s) by which one species becomes another. They are not the same. The problem is that no credible mechanism of transformation has ever been shown.