I think it would be helpful to talk about exactly what quantities one is risk averse about. If we can agree on a toy example, it should be easy to resolve the argument using math.

For instance, I am (reflectively) somewhat risk averse about the amount of money I have. I am not, on top of that, risk averse about the amount of money I gain or lose from a particular action.

Now how about human lives?

I'm not sure if I am risk averse about the amount of human life in all of spacetime.

I think I am risk averse about the number of humans living at once; if you added a second Earth to the solar system, complete with 6.7 billion humans, I don't think that makes the universe twice as good.

I think death events might be even more bad than you would predict from the reduction in human capital, but I am not risk averse about them; 400 deaths sound about twice as bad as 200 deaths if there are 6.7 billion people total.

Nor am I risk averse about the size of my personal contribution to preventing deaths. If I personally save 400 people, that is about twice as good as if I save 200 people.

I'd like to hear how you (and other commenters) feel about each of these measures.