As much as it pains me to inform you...or not so much in this case...unless you are a member of the AAIB, you are not deemed eligible to determine the cause of this.
For the record this guy is by far the best, most experienced, not to mention the safest, pilot I have ever flown with. Need I remind you, you are all speculating using your alleged "intelligence" whereas maybe those who are generally worried will wait for the AAIB report before becoming Einstein.
I understand in the wake of an accident of this kind everyone becomes Sullenberger but seriously some suggestions are utterly ridiculous... We aren't talking about a new PPL with a few hours here.
Just remember all our fellow aviators, this is the chance we take when we step into and aircraft and line up. It isn't up to us to judge. And without becoming morbid, it could be anyone of us tomorrow.
Yet again someone trots out this old copy & paste reply to an accident thread. When will people get the point that they cannot tell this forum what they are and aren't allowed to discuss, and that discussion of the possible causes of accidents is beneficial to flight safety regardless of what turns out to have actually happened. It educates people about what can go wrong, possible intricacies of different aircraft, and helps keep safety at the front of everybody's minds.
"It" could happen to anyone of us tomorrow, as you say; and if that one of us had happened to read about said problem and how to deal with it on PPRuNe today, the outcome might be happier.
You say that those who are "generally" worried will wait for the AAIB. I assume those of us with more specific worries have your permission to keep talking?