I really wasn't arguing that fact. I could argue that there's no evidence that Ven's heart manifested as Sora's nobody but his nobody took Ven's appearance simply because of the presence of Ven's heart inside Sora's. That would be splitting hairs but would explain why Roxas doesn't know that he's Ven.
My point was that Sora unlocked his heart of his own free will and that no matter what he would have (and did) leave a nobody behind. Just as Master Xehanort unlocked his own heart of his own free will. Yes, it did transfer to Terra but he still left his body behind and in doing so created a nobody, which I believe to be MF.
Well MF is Xemnas so.. that would make sense >.<