Machinbird;
Airbus did a brilliant job. The ECAM warnings and drills are extremely well thought out and works providing the crew are very strictly disciplined and follow the ECAM drills to the letter, and right to the very end of the drill. Great confusion/wrong airplane system responses can occur if the crew doesn't do this.
The THS trim wheel moves and is very visible in it's motion in the cockpit, day or night. The only thing it's missing is the noise from the B727's trim wheel. It just goes silently about its business. Trimming using manual trim in an emergency (loss of all electrics - the motors still require hydraulics), is not difficult, (in the sim).
If the initial airspeed errors generated were to the high side of the true value and did not yet exceed rejection criterea, the autothrottle system would throttle back to bring the aircraft back on calculated target speed. As the aircraft slowed, the auto flight system would trim nose up to keep the elevator centered and the aircraft on altitude. Suppose the aircraft lost perhaps 30 knots actual IAS before the airspeed rejection criterea activated and thrust lock activated, throwing the aircraft into alternate law. As long as the aircraft was in alternate law the THS would continue to autotrim and the flight control system would maintain aircraft attitude absent an input from the aircrew, however the aircraft would be seriously under-throttled and decelerating. When the aircraft then transitioned to Direct Law, auto trim would stop, but by then THS position could be very nose up. Of course, Airbus may very well have written protecting limits into their software that would stop this sequence before it progressed this far.
Some research done into speeds may be helpful here plus some understanding of Airbus Reversion Laws when speeds change from computed/commanded for whatever reason. Let's look at the speeds then your assumptions.
Assuming AF447 weights or a bit heavier:
A330-200, 211T, 25%CofG, FL350 (FuelOB 64.9T), Cruise M0.81
TAS..........................................469kts
CAS..........................................274kts
VMO.........................................292kts
Green Dot, (best L/D)...............249kts
Vls, (lowest selectable speed)...214kts
AlphaProt.................................203kts
AlphaMax.................................196kts
In Normal Law, AlphaMax is the maximum angle of attack that can be flown. The airplane can be flown with full backstick and will not stall (go below AlphaMax).
In Alternate Law the airplane will go below this speed without automatic response from the engines but the crew can apply TOGA thrust and execute the standard response to the stall. The stall characteristics are benign although at altitude it can take a lot of sky to ensure recovery and avoid a secondary (to quick to increase AoA) stall.
To your example then, assuming normal cruise speed of 274kts CAS, the airplane is almost 80kts away from AlphaMax speed and 60kts away from the lowest selectable speed. In fact in your 30kts-lost example we can see that the best L/D speed is just under 30kts away from the cruise CAS.
So, to the point, it isn't a matter of 30kts away from difficulty even this early in the flight, (some have suggested the airplane was very close to "coffin corner" - not the case, as shown here). The airplane is no different than any other - the trim does respond to reductions in airspeed as does the autothrust - one sees this especially in mountain waves and while the point is understood, the numbers don't bear out the theory and Airbus has indeed built protections in as described.
One important point which seems to be at odds with your scenario is, the airplane does not revert to Alternate then Direct law merely as a function of reduced speed. Reverting to Alternate Law or Direct law means a loss of data references has occurred and the airplane has no target speeds to maintain. The airplane is a DC8, etc and one must be a pilot, not a manager.
Airbus speed reversions are much less interventionist than Alternate/Direct law. In cruise flight, the a/t maintains speed very tightly. One rarely seems the trim wheel move a great deal.
However, (and only if flying manually) and in a climb or descent and one does not follow the flight directors and either pitches NU beyond commands or levels off before capturing the set altitude without intervening in any other way, the speed will indeed bleed off (because there are no FCU/Autoflight conditions to be satisfied) until about 4kts or so above Vls at which time the a/t reverts to "SPEED" or "MACH" and the engine power increases to regain the last set speed. It can be exciting...but in normal law the airplane will not go below Vls unless in Alternate or Direct Law.
In Alternate 1 or 2 laws or Direct law, it is a "normal" airplane like a DC8 etc and one must fly it incuding the engine thrust.
In short, even in very low speed circumstances as described and with the standard CofG with trim tank full, I think the THS would be a long way from a setting which would take the airplane into a deep/super stall as per Davies' description, all on its own, beyond the control of the crew.
fdr's comments are well worth reviewing, especially regarding the power available....the engines are running at 93% in cruise most of the time. Max CL N1 is around 104% if I recall...there just isn't much more available to either pitch up with or overspeed with (on engine power alone).
PJ2