Presenting the opposing point of view:
1) I see no rewuirement for the cover to be specifically listed as a grounding means; just that there be some method used to prevent the screws from vibrating loose; and,
2) I have, nor has the NEC had, any problem with metal conduit being used as the ground conductor. If anything, this pronciple is reinforced with the new "MC smart,' that does away with the need to have a green wire in MC.
