The normal approach to this scene is to make Cloud female for real, not just crossdressing. But what if all the genders were flipped?
Well, somehow, I imagine it wouldn't work too well. This drabble assumes... a couple of medium to large "problems", shall we say? 
As for why Theo for male Tifa... There's a possibly mistaken belief Tifa's name is derived from Tiffany, which is also derive from Theophania, so, the rest is obvious.