Fuzzy:
I think that Mr. Knoetze's point is that he would like to be able to see some evidence of what exactly happened. This is something that we usually take for granted when aircraft accidents occur- in other words, we take for granted that there will be a proper investigation and that a report of factual findings will be released.
In this particular case, the state in which the accident occurred does not have the resources or the expertise to carry out an investigation, and the two other involved states (South Africa, the state of registry, and the United States of America, the state of the operator of the aircraft) appear to have no desire to investigate the accident.
The NTSB of the USA has provided technical assistance in the form of extracting the data from the FDR. As is right and proper under ICAO Annex 13, they have provided this data to the DRC (state where the accident occurred). Mr. Knoetze has asked South Africa to request this transcript from the DRC, and it appears that South Africa has not yet requested this transcript, or, has not elected to share the information that it reveals with him.
The only way that anyone can determine the cause of this accident with any level of confidence would be to look at the FDR transcript. The record of the aircraft's speed, heading, and rate of descent during the last few minutes of flight would be sufficient to determine if the aircraft hit the ground in controlled flight, or suffered an airframe abnormality of some kind that lead to a descent below MOCA, or suffered a catastrophic failure of one kind or another. Absent this information, everything else is just speculation.