Can you temporarily add some Debug.Log lines in m_playerController.SetControllable() to let you know it's running correctly?
If this only disables player input, you may also need to stop physics, stop animation, clear a velocity variable, or something like that.
If you get stuck, please feel free to send a project to tony (at) pixelcrushers.com and let me know what version of Unity to use. I'll be happy to take a look.