I think platypus didn't notice the quotes around "good" and "bad" and so thought I was expressing an opinion that the reproductively advantageous traits were, in some sense, better than the others; this is a common enough mistake that people have made concerning evolution. Creationists certainly make this mistake when they use the old "if evolution were true, then we should all just selfishly try to propagate our own genes" argument. In hindsight, I should probably have chosen a different set of words to use.
His concern about eugenics, I think, were based on this misinterpretation of the words "good" and "bad".
Kings were put to death long before 21 January 1793. But regicides of earlier times and their followers were interested in attacking the person, not the principle, of the king. They wanted another king, and that was all. It never occurred to them that the throne could remain empty forever. -- Albert Camus