There isn't anything incorrect about what he said there. How it's applied is a matter of ethics.
People survive now with defects that would have killed us in a more primitive time. We certainly pass those defects on much more frequently now than we did when those defects would have killed us. We certainly have many diseases and weaknesses that are genetic. And a genetic predisposition to cancers in some families stops few from deciding to have children. Such predispositions to have cancer or bad eyesight would prevent any breeder of animals to decide not to breed a particular animal, but because it's not socially limiting, we are a society now where it is common to have genetic cancers and bad eyesight requiring glasses even as young children. Is that a good thing?
There was more but I'm busy at work and didn't have time to find it. However, I wonder if that is taught in schools as well.