Epistemic status: elaborating on a topic by using math on it; making the implicit explicit
From an collective standpoint, the utility function over #humans looks like this: it starts at 0 when there are 0 humans, slowly rises until it reaches “recolonization potential”, then rapidly shoots up, eventually slowing down but still linear. However, from an individual standpoint, the utility function is just 0 for death, 1 for life. Because of the shape of the collective utility function, you want to “disentangle” deaths, but the individual doesn’t have the same incentive.
I agree that #humans has decreasing marginal returns at these scales—I meant linear in the asymptotic sense. (This is important because large numbers of possible future humans depend on humanity surviving today; if the world was going to end in a year then (a) would be better than (b). In other words, the point of recovering is to have lots of utility in the future.)
I don’t think most people care about their genes surviving into the far future. (If your reasoning is evolutionary, then read this if you haven’t already.) I agree that many people care about the far future, though.