Feif Un: the blade of a Norelco is plenty sharp enough to cut without the help of any other blade, there is no scissor action involved. Therefore the remaining issue is that even a razor may be used to cut the beard at a distance from the skin.
mariner: the blade is parallel to the skin, that’s why you don’t get nicked. Too close is not a problem if there is a scissor action, and would not be a reason to forbid.