I thought the original point was to focus just on the inconvenience of the dust, rather than simply propositioning that out of 3^^^3 people who were dustspecked, one person would've gotten something worse than 50 years of torture as a consequence of the dust speck. The latter is not even an ethical dilemma, it's merely an (entirely baseless but somewhat plausible) assertion about the consequences of dust specks in the eyes.