I don't think it was ever said that she was half-human, was it? The remarkable thing was that she was born to a replicant parent, but that could well have been two replicant parents. 2049 never stated a position on the matter as far as I can remember
I'm pretty sure he would have, although I can't imagine that he would have been going there to "retire" Sapper in the first place. While his actions at the end of the film weren't against his old duties for the police, he seemed all in for the replicant cause by the end of the film. The thing Sapper said about "because you've never seen a miracle" turned out to be spot on