Stick_Rudder, I'm not an authority on the subject, but family members might not know of its significance if Parasomnia events had occurred, and that would only be an indicator of a tendency. My own event has not been repeated to the best of my knowledge in a span of almost 50 years.
As to whether it was possible to have a pilot function to that level of performance that the Captain exhibited, I guess if you can have a nightmare about an event, you can have a parasomnia event given the right circumstances. The Captain exhibited way too much focus on a single path of action. The conscious mind is exploring alternatives.