I'll betcha that fin came off and precip'd the accident sequence.
That is a bold bet BB. There are a lot of people at BEA who would stake their professional reputations on you being wrong. Can I get a piece of the bet too
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Have you been reading that A319 wake turbulence incident that SensorValidation mentioned recently? That aircraft overstressed its VS attach points but without causing permanent damage.
I found the trace of that aircraft's flight control inputs vs surface positions pretty clearly showed some control rate limiting occuring.
Unfortunately the graphic is a bit fuzzy, but if you print it out full size you can then easily read the legends along the margins.
A wake turbulence encounter is probably a good comparison with what happens inside a developed Cb, only perhaps a bit gentler.
If you look at the elevator trace, you will notice one side of the elevator lagging the other side. This is probably the result of its active hydraulic system not keeping up with the demand in that time frame. Later (after the vertical green line) you can see the rudder doing something quite different than what the pedals are commanding. Probably a good thing that the wake encounter only lasted a few seconds.