I personally believe there is no way for them to succeed. If they were acting in good faith the actual incease in the number of intelligent people, who would recognize cruelty when they see it, would tear it down. If they acted in bad faith, which they most definitely would, they would fill the world with these idiots.
Youre not supporting the idea of eugenics because you know it to be lunacy. If they were acting in good faith, the more intelligent society would recognize the lunacy as well. If not they would remain dumb.
Science is consistent. If mankind started over from scratch, they would eventually come to the same scientific conclusions as us.
Society and morality is VERY abstract and every society has their own unique spin on it. We have no idea what societal structures would exist after a hypothetical human reset.
Democracy revolves around “every body has value”, and in that light, elimination of “inferior” people is horrific.
But eugenics is more of a “sacrifice some for the greater good” kind of belief, and they would believe that their actions are morally superior to the “selfishness of having unauthorized offspring”.
Societies have 100% operated under other moral structures. Under the moral operative that human life is inherently valuable our society has progressed further then any other recorded civilization.