In the 1920s and 1930s, scientists from both the political left and right would not have found the idea of designer babies particularly dangerous - though, of course, they would not have used that phrase.
But failure to disprove something is not a good reason to believe it.
We are a unique ape. We have language. Other animals have systems of communication that fall far short of that. They don't have the same ability to communicate complicated conditionals and what-ifs and talk about things that are not present.
Let us understand what our own selfish genes are up to because we may then at least have the chance to upset their designs.
If something is true, no amount of wishful thinking will change it.
Once a viral program gets started, there is nothing to stop it.