Cant say i have seen anything about the VQ crank being specially coated, it could be Nitrided but most forms wont preclude grinding, yes a decent engineering company that is used to crank grinding will grind the journal to the tolerances for the manufactured oversize bearing, which means it will fit and have the correct crush tolerance when fitted without ever having to use plastiguage or similar.
I can't quite remember what the reason was tbh, maybe I've misunderstood or they were talking about wear on the block that holds the bearings or something, either way I'm just glad my crank wasn't worn