|Since this is literally a problem in name only, you should honor this new employee's request and call him whatever he prefers. Perhaps the only exception is if his nickname is a derogatory or offensive term. In such a case, you can suggest that he use his given name or even another nickname if he feels so inclined. |
Assuming that his nickname is not going to insult anyone, you have no reason to feel like a fool when you introduce him to the rest of your staff. In fact, a unique nickname can be a great icebreaker to open all sorts of conversations with his new co-workers. After all, if his nickname had created work-related problems in the past, he would have dropped it.
You are focusing on how you will look when you introduce him, and you should be focusing on providing him with an excellent orientation, challenging responsibilities, recognition for his successes, and an opportunity to grow and advance. He's not bothered by his nickname, and it should not bother you either.