I think you are applying utilitarianism to a point where it is no longer useful. Sure, I guess if a dissident is executed we might as well make good use of it, right? But this misses the forest for the trees. An ethical climate like this makes for a worse society overall, since people will naturally be inclined to do worse things out of their own subjective interpretation of utilitarian value. In a place where people try to aim for abstract and idealistic moral values, you paradoxically have a situation where life gets easier as there is an additional mental block against poor incentive cycles such as arresting more dissidents and destroying more families to have more organs.
There's a reason why abstract moral frameworks like abrahamic religion have enjoyed a good evolutionary run. Ultimately calculating utility in a helpful way is an almost impossible task for a group humans with different aims. That's why the satisfaction of coming up with edgy utilitarian conclusions is in fact a red herring.
His medical defence was specifically denied as he did nothing to contribute to the Nazi war effort.
He did none of the valid, but unethical, Nazi research like the well known hypothermia experiments.