 Because the device locked on to his Digital signature, he could never go back to being a human even if he was defeated.Before Nitta vanishes, he tells Yoshino to tell his daughter that he loves her.He also reveals that Kagura has the Code Key of Wrath, thus he has all the Code Keys (Wrath, Gluttony, Greed, Sloth, Envy and Lust) to unseal Lucemon.