No one that has been involved in accident investigation would have any 'belief' in what the 'cause' is at this stage. A key part to being an investigator is to not jump to conclusions until you have as much information as possible. Putting forward 'beliefs' can bias the investigation to 'fit' the outcome you want. You get all the data, witness statements, as much information as possible and then start ruling out what it's not from a list of possibilities that you have made up based on the scenario. The pilot may have had a heart attack after a wing fell off, so if the autopsy found he had died before impact, but you never bother to look for the wing, of course it goes down as an incapacitation instead of inflight break up. And further to that, several posts have indicated why this does not necessarily fit with an incapacitation, first and foremost that the aircraft basically plunged straight down, but not at VNE, even though it was near vertical.