At least one point of Three Worlds Collide is to help the reader appreciate what Irreconcilable Moral Differences feel like from the inside. Humanity revising its view of consent contributes to this goal, and has the benefit of being nearer. With immortality to keep past generations alive, sufficient cumulative moral progress will feel to them about as alien and terrible as legalizing rape.
At least one point of Three Worlds Collide is to help the reader appreciate what Irreconcilable Moral Differences feel like from the inside. Humanity revising its view of consent contributes to this goal, and has the benefit of being nearer. With immortality to keep past generations alive, sufficient cumulative moral progress will feel to them about as alien and terrible as legalizing rape.