The only way I could see of seriously addressing the problem while remaining true to progressivist principles would be a global eugenics program overseen by a democratic world government.

This is a good illustration of the difference between how Progressives and NRx approach problems.

First a Neoreactionary would point out the obvious problem with this approach: you have democratic governments attempting to implement eugenic policies which will affect what the future voters will be like. Thus this system has a very strong and undesirable attractor, namely the politicians eugenically breed the kind of people who will reelect them.

The NRx approach to dealing with proliferation of low time preference people is to reduce/eliminate the welfare state and let them die out as a natural consequence of their own short sighted behavior.