This is a pretty bad summary of Bostrom's views at least.
It's not about an ethical obligation to create digital people, more a way to quantify what's at stake if humanity were to be destroyed. The point that he makes is that most people use 8B deaths as the "cost" when doing cost benefit analysis around a hypothetical apocalypse. Bostrom thinks the cost is much higher since it should also include all humans that will ever exist. When you try to quantify how large that could possibly be, you run into the possibility of far-future digital humans and he includes those in his calculation.
IMO it sounds high but not ridiculous for the Bay Area but I'm not familiar with market rates in Europe. A few thoughts generally:
1) Did you raise enough money to afford this? Does it meaningfully decrease burn? 2) If you think of this person as a key hire instead of a founder are they worth the high salary + high equity?
3) Are your VC's OK with it?
4) If you require much less salary you can may be able to use it as a negotiation point to change your equity split
5) One argument for paying comfortable salaries is it allows founders to be more long-term minded and to ignore early exists. There's a sense in which being broke makes you irrational so not having your exec team worry about personal finances could be a good thing for the business.
Good luck with this! negotiations between business partners are always tough.