Pointing out self refuting arguments is great and all and although I believe you are correct when you try to question “right and wrong” with an atheist, many times it does become a circular argument. I believe the question falls flat even without necessarily invoking its self refuting nature.

There are things we do for the welfare of mankind and this makes them right and wrong.

I would reply, saying that yes, “properly” and “judiciously” managed, eugenics would help mankind but it is always wrong because it tramples the rights of the individual.

So the atheist has a choice to a) accept my position and agree that individuals have rights or b) come up with another reason why eugenics is wrong or c) go ahead and say eugenics is right because it’s a thing we can do for the welfare of mankind.

No matter what the response, I have made more progress in the discussion than someone who merely points to the self refuting nature of the argument. I can always call it quits when I’m tired of the discussion by asking what objective sources inform his current position. Just a different approach.