This whole argument only washes if you assume that things work "normally" (eg like they do in the real field, eg are subject to the axioms that make addition/subtraction/calculus work). In fact we know that utility doesn't behave normally when considering multiple agents (as proved by arrows impossibility theorm), so the "correct" answer is that we can't have a true pareto-optimal solution to the eye-dust-vs-torture problem. There is no reason why you couldn't contstruct a ring/field/group for utility which produced some of the solutions the OP dismisses, and in fact IMO those would be better representations of human utility than a straight normal interpretation.
This whole argument only washes if you assume that things work "normally" (eg like they do in the real field, eg are subject to the axioms that make addition/subtraction/calculus work). In fact we know that utility doesn't behave normally when considering multiple agents (as proved by arrows impossibility theorm), so the "correct" answer is that we can't have a true pareto-optimal solution to the eye-dust-vs-torture problem. There is no reason why you couldn't contstruct a ring/field/group for utility which produced some of the solutions the OP dismisses, and in fact IMO those would be better representations of human utility than a straight normal interpretation.