When Hades sang "You’d shine like a diamond down in the mine", I heard it as a direct call-out to Tom Waits' "Heigh Ho".

As for whether Hades is or is not the Devil, I found the line "Who makes work for idle hands?" to be both powerful, and to inform my ongoing dissatisfaction with late-stage capitalism. In addition to the traditional answer of "the Devil", there's the possible answer "Me, Hades" (or by extension, any "job-creator" (who all really deserve a tax break)), and also "people who support workfare".