It seems important at this stage to have an open mind about the captains actions as the full sequence of events does not appear to be public. It is certainly unfair to denigrate on the basis that no-one ever should make a mistake. On the one hand you could draw comparisons to ensuring the absence of control movement restrictions as a fundamental rule, and even with an everyday scenario such as letting a coke can roll under the brake pedal in a car - clearly driver error as it is a well known risk. On the other hand the flat surfaces in an airbus cockpit do seem rather innocent places to put things, ignoring hindsight etc., so perhaps this mistake is fundamentally forgivable - the first time etc.
There remain some questions though about how obvious it was the camera was the cause. As the ac started to pitch down, surely the first instinct would be to reach for the stick, at which stage its forward displaced or jammed(?) state would become apparent or obvious? Was the seat motored back immediately afterwards?
Was this crew a classic 'always in the RAF' RAF crew or one of the hybrid ex-civ A330 crews (if I understood correctly that they were recruited and exist flying voyager, and if they are still around on the programme?)