I have a 1 year old and a three year old and bedtime is 7pm for both of them. Studies show that children who stay up later do not do as well in school and are not able to focus as well as children who go to bed earlier. My personal opinion is that putting a two year old to bed any later than 8ish is not in the best interests of the child.

That being said, some kids just require less sleep than others so if he is able to focus (as well as a two year old can, anyway) and is not overly crabby then more power to them.