My dd doesn't nap at all, and hasn't in at least 6 months. I think you have to look at the total number of sleep hours in 24. Even from reading the responses, it looks to me like the average 2yr old is getting around 12hrs of sleep in 24hrs. Some all at night (like my dd, who goes to bed between 7:30-8:30 & gets up around 8-9) and others more broken w/a nap.
I'm a not an early person (and neither is my dd or my dh thank goodness), so if I had a 5am riser, I think I'd do what cmb123 suggested, provide toys/snack for them to play, but set limits as to when i'm getting out of bed. I think a 2yr old can understand the concept, and although they may not like it at first, he should be able to entertain himself until a more reasonable hour.