That would be interesting, we don't know a lot about him, and that waiter is really old. XDMaybe he's all of them and is just being a double/triple agent in plain sight. What better place to gather intel than on a famous restaurant by having a convenient excuse to wander around near the tables? Wouldn't that be a twist.
Though, now that I think about it, dark elves don't live a whole lot longer than humans, at least not compared to their brethren. So, maybe, the dark elves from that time would be dead by now, but it was only about 100 years ago, so it's possible, though pushing it.