As well as having two counter-rotating elements to kill the gyroscopic problems, you probably also need a speed-limiting mechanism (or for fail-safe, more than one).

Like the governor on a steam engine that opens the relief valve if a safe speed is exceeded, you could either engage a brake if speed and angular momentum get too high, or have spring-loaded vanes that automatically spill the wind if it's too strong, or have spoilers that deploy above a certain rpm etc.

best to have a passive rather than active mechanism - brakes can burn out or jam on. Vanes that spill the wind are a good idea, and you can have several levels of fall-back to accommodate wide variations of wind.