As I have noted before on this forum, most people advancing person-affecting views tend to opt for asymmetric versions where future bad lives matter but future good lives don’t. If you’re temporally neutral and aggregative, then you end up with a moral theory which is practically exactly the same as negative utiltiarianism (priorities one two three four etc are preventing future suffering
If someone did take an asymmetric view and really committed to it, I would think you should probably be in favour of increasing existential risk, as that removes the possibility of future suffering, rather trying to reduce existential risk. I suppose you might have some (not obviously plausible) story you had about how humanity’s survival decreases future suffering: You could think humans will remove misery in surviving non-humans if humans dodge existential risk, but this misery wouldn’t be averted if humans went extinct but other life keep living.
If someone did take an asymmetric view and really committed to it, I would think you should probably be in favour of increasing existential risk, as that removes the possibility of future suffering, rather trying to reduce existential risk. I suppose you might have some (not obviously plausible) story you had about how humanity’s survival decreases future suffering: You could think humans will remove misery in surviving non-humans if humans dodge existential risk, but this misery wouldn’t be averted if humans went extinct but other life keep living.
I think the argument is as you describe in the last sentence, though I haven’t engaged much with the NUs on this.