Good catch, I'm well aware of that. I didn't say that I think bringing a neutral being into existence is neutral. If the neutral being's life contains suffering, then the suffering counts negatively. Prior-existence views seem to not work without the inconsistency you pointed out. The only consistent alternative to total utiltiarianism is, as I see it currently, negative utilitarianism. Which has its own repugnant conclusions (e.g. anti-natalism), but for several reasons I find those easier to accept.