...ie what would the average competent pilot do here?
A competent pilot driving in darkness toward known convective activity would have his eyes glued to the attitude indicator and occasionally cross check other indicators. As soon as the autopilot clicks off a competent pilot would take a deep breath and look about for possible reasons, but not do anything unless the flight path of the aircraft is changing. If the aircraft had been in trim before autopilot disconnect, there would not be any major departures from the previous attitude, unless there is a flight control system hiccup.
I have read, and reread, the BEA note over and over and I do not see any direct statement that the pitch up of AF447 was uncommanded. If someone else sees otherwise, let me know.
Someone earlier stated that, ordinarily, an autopilot disconnect should not be considered an emergency yet it appears that many AB pilots think it is. Clearly the AF447 pilot thought that way and he acted inappropriately.