Is it not something to do with working in a food environment?

Im only guessing here but im pretty sure Asda sell food, in which case doesn't health & safety require you to cover any ear / nose piercings or remove them whilst in that environment? If so I would guess it falls into the same criteria?

Hope you dont loose your job over it tho. I was made to remove excessive ear piercings when I worked for John Lewis..... after a week I couldn't get the damn things back in, was well pissed off but didnt think it was worth loosing my job over.