Is there? I honestly don't know it.
Well there are several reasons why this shouldn't be added in my opinion. I would assume that one of them was the reason why this game hasn't been added (oh, and obviously there IS a reason why it hasn't been added, else it would've been added!)
1) We don't have Sonic Shuffle charts. If you have one, I'd argue we should add the other. And high scores for Secret Ring party games.
2) There wouldn't be enough competitors to make it worthwhile I don't think.
3) Best times and scores are already covered by Nintendo Wi-Fi. (If we were to do as Shadowfan seems to suggest, and have individual divisions for each character, this argument wouldn't apply, but that would be a LOT of charts (17*amount of competable events))
4) It's a pretty boring game
5) A lot of things on there are maxed, and not improvable. It's not like other charts here where new strategies can be found, meaning that competition keeps on going. It would just...die.
Individually, these reasons aren't really reasons not to include the game. However, with all of them, I think it is a fairly strong argument. That being said, if Mario and Sonic at the Olympic Games charts were added, I would compete (so with Azure and I, that's 2 competitors already!)