Some thoughts (and a first post) from a humble engineer
On the right turn:
In the BEA google earth graphic, the right turn commences after point "6." It is stated after this point in the text that the PF makes inputs to the nose up and roll left stops. Assuming (note: I have far less than the near-encyclopedic knowledge of the Airbus Flight Control system than many others here) that in this case, spoilers 2-6 and the IB/OB aileron on the left wing are raised to a significant degree, the effective camber of the left wing is reduced. We know that at least in the conventional stall and approach to stall, decreased camber results in decreased overall lift, but also
increased stall AoA (see
Figure 2. Effect of Trailing-Edge Flap and Speed Brake Position for the cool graphic).
These guys were so far to the right of a conventional Cl/alpha curve, I won't comment as to the lift, but it does make sense that for
some AoA near or beyond the stall AoA that the deflected ailerons and spoilers delayed separation or at least moved the separation point rearward compared to the right wing. Seems to me it's plausible this could result in lower drag on the left wing and a net yaw moment to the right. It would take those more in the know that me to comment on which direction the roll moment would be in this case.
I speculate that at some AoA, the left wing, like the right wing, becomes a very finely machined barn door, and the aileron/spoiler position becomes irrelevant.
Further speculating beyond my cubicle, this presents a weird control situation. Stick left would produce a yaw to the right. Stick back increases AoA and cancels any lift or drag asymmetry (zero roll/yaw moment) between the two wings. And, it has the nasty effect of canceling the stall warning. Stick forward gives the stall warning again and possibly the yaw sensitivity to roll inputs. In this (speculative) scenario, I can easily the psychological appeal of stick back and TOGA power (more to come on this later).
I can positively say that I'd never solve a puzzle like this in 38,000 ft, but my pilot in command experience is measured in airsick bags instead of hours - I'd appreciate thoughts from those of you that actually did this for a living.