The theme that played when Fi's trophy was shown is the Ballad of the Goddess, which is the main theme of Skyward Sword and an important song in the game's plot (fun fact: it's Zelda's Lullaby backwards). I wouldn't say it really hints towards Ghirahim in particular, but it may possibly hint towards a Skyward Sword character.
That's what I tough, but I don't know, I heard that the Ghirahim heme was based on the main theme.
Problem is, if it is the main theme, it's not specific if you consider as a zelda theme. It doesn't matter if she's confirmed because the tease should be specific enough to not doubt.
Ridley is his theme, just that settles it. I can't doubt the relation.
Robin is very specific as like I don't even consider being someone else.
Palutena is too obvious.
But here? That's so weird.
Seriously, it's a riddle game now. Trying to find which character that ONLY HIM has a unique relation to Fi AND ballad of goddess.
I'll have to think about it, but for now, it's a zelda newcomer as placeholder.