This is the only issue with RR clears. People don't consider the context when RR is almost entirely based on specific niches being fulfilled (TRodya carrying RR4 for example)
>Why is Mariachi Sinclair used?
Low speed that helps ensure he goes last and lands the killing blows.
The team needed a lot of gluttony as they were running out, and Sinclair had both
>Tarnished blood (gluttony and a strong EGO to boot)
and
>Impending day (gain 5 resources of whatever sin killed an enemy)
him killing multiple enemies with it during the second round generates 15 gluttony resources and another 10 when he kills Nicolina and Curiambro. Enough for the ego usage required.