I think he could actually be a fae, and make it good. As stated earlier he had the summer of 07 getting cheers. And with them saying that it might be revealed that he can talk, that would probably turn into a comedy act with him trying to learn how to learn/speak English week after week. Have somebody like Eve maybe be his helper, since she stated she wanted to be a wrestler.
Storyline ways, Eve would be teaching Umaga English, guys would laugh at him, he gets mad and goes all out for them laughing at him. The (heel) divas would laugh at her for helping "an animal" or taming "an animal", she gets mad with them, meaning more ring time for her as well. That's just one way it could work but I don't see it as another Khali and it certainly wouldn't kill Umaga's character. And if the fans don't get behind the idea, they could easily have Umaga turn on Eve and get his heel heat back.