How does that negative utility vary over time though? Because if it stays the same (or increases) then if we know now it's impossible to live 3^^^3 years, then disutility from death sooner than that is counterbalanced (or more than that) by averted disutility from dying later, meaning decisions made are basically the same as if you didn't disvalue death (or as if you valued it).
I think that part of the badness of death is the destruction of that person's accumulated experience. Thus the negative utility of death does indeed increase over time. However this is counterbalanced by the positive utility of their continued existence. If someone lives to 70 rather than 50 then we're happy because the 20 extra years of life were worth more than the worsening of the death event.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.