It means that if something is physically possible, someone will be doing it, regardless of legal, moral, or social barriers. False on its face? Not that long ago, global public opinion was mortified at the news, that newborn twins in China have been genetically modified. I am old enough to remember the outrage in the late 90s as the world watched the first cloned sheep grow up, get sick, and die. It was possible to do, so someone had done it.

The point is - with the use of law, morality, social pressure, we can moderate the frequency and scale of some phenomena, but we cannot stop it. I think this idea is what prevents some bans. "If the Chinese can do it, and we stop ourselves from doing it, they will gain an advantage and we would lose". Substitute "the Chinese" with whoever is the opponent at any given point in time and you have a rather plausible explanation for why things were the way they were.