I certainly agree that werewolves shouldn't talk - Aela in the Underforge never said a word during the Circle induction, and the odd human-voiced comment thrown by a fighting Circle werewolf to me is a game mechanic error. However, Sinding NEEDS to communicate with the player, and NEEDS to be a werewolf at the time. I'm wondering if someone can't modify his lines at this stage to where it sounds more spacey, like he's talking in your head or something - just not through a wolf-snout full of fangs.
I started thinking about it after my last post though, and a werewolf follower would actually be rather interesting if done right. I'd love to have to escort an uncontrolled werewolf across Skyrim in search of a cure (a werewolf who can't control their transformations). Maybe get some audio/visual cues when your follower is about to change, to give you a few moments to get him to an unpopulated area. Even have to punch him upside the head if he gets spritely with me, or whip out some special anti-wolf amulet or wolfsbane to keep him off me until he turns human again.
I have fun with followers in-game as it is (I pretend their pathing difficulties are due to their seeing so many new things on their adventures that they get distracted), so a troublesome follower would be right up my alley.