I really don't get what her being a PoH has to do with wielding. From what Nomura said, in order to wield a person as to 1) touch a master's keyblade 2) have a strong heart (and presumably be chosen by the keyblade as a result). She touched Aqua's keyblade, and since she was seen wielding in KH2 it can be inferred that she does indeed have a strong heart. Where does PoH-ness even come in?
They are saying that her having a heart full of light makes it strong.