That is truly morally ambiguous, but wasting his intellect would not put man on the moon.
So its the matter of valuation (quite impossible task), but then again when a plane crashes someone has to calculate how much your relatives' life were worth to pay compensation.
That's probably the logic behind what happen to nazi scientists. They were worth more alive then dead (also both sides were hunting for them not just USA).
I agree it's not cut and dry.
However, we cannot be sure we wouldn't have reached the moon or achieved other great things without Operation Paperclip. It's not like all the rocket scientists were Nazi elites. E.g. Goddard was American.
https://en.wikipedia.org/wiki/Wernher_von_Braun
TLDR the Nazis used slave labor to build V2s, and then the USA hired the slave masters (and ensures they didn't stand trial at Nuremberg)