The statement:
An initial wreckage layout confirmed that all major airframe structure was located at the accident site.
I take that to mean that both wings were attached to the fusealge to the end. In a high speed turn that tight, if a wing had gone wrong, it would be farther from the main wreckage.
If this were a crash in VFR flight with poor reference to the surface, it would have similarities to JFK jr's accident, loss of reference, entered spiral dive, pulled to try to recover. But, it sounds like the weather conditions would not be a factor. So, loss of control. The initial turn to the left, which included a climb from 5400 to 5600 feet, reduced radius noticeably just before a sudden and tightening turn to the right with descent, never recovered. Perhaps some said "hey look at that..." and the pilot steepend the bank, so as to see around the wing, while slowing down, while carrying a heavy load. In a climbing turn, a stall entry will typically result in the drop of the opposite wing, and if not recovered immediately, a spin entry opposite to the direction of the turn.
I opine, based only upon what I read in the report.