No, I'd hate to see Ghirahim in Smash Bros, 'specially since he's essentially a one time villain for the most part.
As I and others have stated before, that's not a legitimate reason. Vaati101 nailed it when he pointed out that Lucario (whom I never expected to get in) was only in one game (and movie) yet made it into Brawl. It wouldn't be the first time Nintendo did this sort of thing in Smash Bros.
Point is, with Ghirahim's SS moveset, he isn't unique to the SSB series outside of his flamboyant looks. He'll need some heavy expansion to make the roster.
You mean like they did with Zelda/Sheik? They'd certainly make him a great fighter.