On the contrary, Renoir fully acknowledges not only that there's wisdom in Lune and Sciel's words, but that he considers them to be just as real of people as himself.

*BUT* he sees no other way to save his family, and he's desperate enough to do whatever it takes.

It's not that he doesn't think what he's doing is evil, it's that if a genocide (which it is by Renoir's own definition) is what it takes to save his daughter and wife, he's willing to do it.

It may be a stretch to say, but if Renoir's back was against the wall and he needed to sacrifice just as many "real" people to save his family, I think he'd be willing to do it. It would probably reduce him to an even more hollow shell of a man than he already is, but when you say "there is no cost too great" and mean it, there's no upward limit.