That actually matches with how most people view things though. The utility of eating anyone is going to be extremely small, especially compared to the opportunity cost of a person's life, so the only time you're going to get that situation is when someone can be expected to cause so much harm to others in the future as to outweigh their own life, such as, for example, how someone who kills someone that's attempting to commit mass-murder is usually considered justified in doing so, or if you're in trolley-problem scenario where saving multiple other people necessarily requires the death of one person.

Setting the scale to not have negative values in a non-relative sense is just to prevent issues like it becoming a good thing to kill sufficiently unhappy people, even if they object and there's no danger to anyone else averted by doing so.