Are you sure it doesn't furl. (I found catalog entries for windtalker windmills on the web that seem to claim they furl at "25" (mph?).)
The mill may furl by stalling (allowing the airflow to detach from the blades at high wind speeds when loaded). As the wind rises to a high level does it go from reasonably quiet to very loud (making "helicopter sounds") over a reasonably narrow range of wind speeds? That would be a symptom of stall furling.
There are a number of other ways to furl a mill besides folding up the tail to turn it away from the wind.
If the mill is furling properly it will lose torque and won't overspeed in high winds (at least up to some design level). So all you have to do is protect your batteries against overcharge (say, with a dump load) if the mill doesn't and you're fine.
You might want to contact the manufacturer and ask how and whether it furls, how high a wind it can stand when operating normally, and what to do to protect it in higher winds.