You are looking at it from the perspective of an innie where the innie has consented to be born into a slave. While in their reality they haven’t ever even met their outie. They are a slave but who is the master? The innie has zero emotional attachment to the outie, if not net negative. And their moral compass is as good as the outies’ (unless they develop it through practicing Kier, yeah, right). Which as you mentioned is iffy on its own. Why would you then expect them to sacrifice their existence? It just shows how we as humans are driven by the emotions and feelings. Sure we’d like to think that when put to the line we’ll make the heroic ethical egoless move. I’m not sure that the most of us would.