Also, I don't see him comparing eugenics to evolution. He's went on to say, 'just because it's morally wrong, doesn't mean it's not possible', which was the point he was making.
See my reply to the sibling comment -- briefly, variety is the driver of evolution, not selection. The more you constrain variety, the worse off the population is from an evolutionary perspective. Any attempt is net negative, a large-scale attempt would be disastrous, regardless of the moral or ethical implications.