Air Traffic "Control" in that area? HF! 20mins spacing with same M-number! Anachronism! That's why all smart pilots northbound ask for max FL within Recife (Radar), because they won't get FL-changes from Sal or Dakar within the next 3 hours or so. As AMF correctly posted: Here you are, heavy at maxFL, in the coffin corner, close to low and high speed limits. If you get positive windshears/updrafts, Auto Thrust/Auto Throttle will reduce power. In a strong positive shear that might not be enough. The airplane enters into overspeed. At about 6 knots (?) in the overspeed regime, the Auto Pilot disengages and overspeed protection mode let's the airplane climb to avoid a further possible destructive speed increase. Normally, when airspeed reduces below "barber pole", the auto pilot should be engaged again (FL-CH/Open-Descent), and will smoothly descent again. Airbus pilots should know this ( is this trained by AI and AF?).
If you decide to fly manually- still slightly in overspeed- sidestick inputs (e.g. down) are restricted, until you come out of the overspeed range. Manual flight at that altitude, may it be with a Boeing or Airbus, is never an easy task and not really recommended.
If the pilots decide to give a sidestick-down-input still in overspeed, to descent back or to reduce pitch, the manual inputs are dampened, until the aircraft comes out of overspeed. Coming out of overspeed, the (now not any further restricted) input might be too large, resulting in possible minus-g , and possibly many hurt passengers, as has happened before in incidents. Structural damage might be possible, depending on g-force.
Let's hope they find the Red Box(es).
Be safe.