the groups that nazis target for extermination can't change who they are. they can't stop being black or gay or jewish or trans or whatever. but nazis can choose to stop being nazis. that's why their lives don't matter. they have made the choice to embrace fascism, an ideology that demands the death of nearly everyone on this planet. until and unless they change their beliefs, their deaths are necessary to protect the rest of us from them.
it is always morally correct to kill a nazi. every nazi killed is an innocent life saved.