See it could make sense and be awesome if he was a huge Heel but they are not playing him off as one at all.... If he was a Heel and champion his size would be a huge part of the storyline with Bryan having to overcome another hurdle for the title.
He has no personality. I think something that might work for him is lets say he takes a bump to his throat or something that would make it so he couldn't talk. I just find something frightening about that. He could turn heel and start off like Kane did with going to the ring and taking out everyone. As far him being champion with his current gimmick I just think it would be way too bland.