"Regardless of what any official report might say, people who knew Martin well know that this accident was caused by something catastrophic happening to the aircraft that rendered it unflyable with no time to do very much about it. "
Foxcotte, I knew Martin very briefly, but know the operator. While I am inclined to agree with your statement above to a point, all operators of Caravans in Maun limit the load to pilot + 10 out of Xaxanaka. There is a reason for this. Even with a full load, on a winter morning it can be hairy in a van.
So, 1 extra pax on board, midday October, the hottest month of the year - it's not ideal, more so if there was a mechanical failure of some sort, because he would have had to nurse that plane into the air in the first place.
The unfortunate thing about this incident, is your further comment
"1. Martin had just resigned from Moremi because he wasn't happy with their operations."
Perhaps this may also have clouded his judgement of taking such a heavy load, and just "getting the flight done" or perhaps have had some effect on his thought process, we all know how stress can affect us all.
I really do hope CAAB take your comment in to account with investigation, the company has had quite a few accidents over the last 3 years - clearly something is not right.