I wouldn't be too impressed if that happened to me while I was dining. I'm a manager at a restaurant and if I ever saw one of my staff doing/saying that to a customer I'd have a quiet word with them saying that it doesn't matter what cutlery someone uses - the easiest way to deal with that situation would to just let the diner use whatever cutlery they fancy and once that course is cleared to just replace the cutlery setting as need be. Luckily I've not had to talk to a member of my staff about that as they are all on the ball with that and are attentive so they can rectify any cutlery situation between courses.