A couple of questions re the location and security of the captain.
It is assumed that he was in the rest area. If the turbulence was really bad, as is being made out, why would he be unrestrained? If the forecast weather and the experienced actual weather (turbulence, dense CB and lightning) was as bad as is being portrayed, why wouldn't he be on the flight deck where his experience and route knowledge would be at its most useful?
Of course he may have been unrestrained because he was returning to the flight deck at the time of the accident but his assumed absence from the flight deck raises possible questions about the decision not to be in command at a potentially difficult period and adds to the concerns already highlighted about the fuel upload.
I've a particular interest in this accident as I've family in Rio, have flown the route with BA (quite satisfactorily) but AF - which many non-French ex pats in Rio are avoiding at present, not necessarily logically but some at the insistence of their companies - may well have to be used by various family members from time to time.