It wouldn't matter either way. Don't even give them the hypothetical. If we can be tortured for some miniscule eugenic benefit that is less moral of an option than just a concentration camp style final solution. Just do it right one time, take control over the gene flow afterwards and end the suffering for the long term.
None of them would support that. If they wanted to make the eugenics argument, there would be so many other areas they would have to apply this to in ways they are not comfortable with at all. The amount of benefit our plight can possibly result in through eugnics is not big enough to make a difference once you quantify it. It's just a shit line of argument any way you look at it, even before you find out how dysgenic female selection in the modern world is at times.