Not at all. FCS2 requires Rosetta to install, not to run. Same with Office '08. With such huge, expensive, and mainstream software packages working like that, it would not be surprising to see some games the same way.
If the game is installed right now, you can get info on the application and see if it's Universal or not. If it is, and you upgrade in place, you'll be able to run it under Lion (barring any graphical issues or other random quirks that come with running games on OSs more advanced than when the game came out).