Surely pilot fatigue leading to errors in judgement both in the planning and execution of the task has to be a factor here. How else to explain what we see? Blancolirio’s analysis is valid, but how did they ever get into that predicament when it seemed to have been not really necessary for protection of either life or assets anyway? Perhaps the inquiry will reveal whether they were operating under a request to drop at that spot, or operating under their own initiative ....
A further point if I may.... Without having even the faintest idea of how aerial fighting is 'managed' outside of my own involvement in one of the 'down under' regions, it used to be (and possibly still is) a requirement here for lots of hours (thousands I seem to recall) in aerial ag operations before one could strap on an aircraft loaded with fire fighting product and head off towards the smoke on the horizon. The reasons are / were that you need a lot of experience operating a loaded aircraft close to the ground in a wide variety of situations and terrain in relatively benign conditions before entering into the additional unknowns of variable visibility, extreme turbulence, heat, and often windy conditions in totally foreign terrain. I don't know how many hours the PIC had in low level fire operations, but somehow he was seduced into a manoeuvre which was destined to end badly.
Finally, does anyone know the crew configuration for these ops? - two pilots or pilot and observer / mission director? If only one of the crew was PF, and was flying from the LH seat, it seems probable that the precise location of the target for the drop would have been partially or totally obscured for much of the approach. Perhaps that could explain the sudden increase in bank once it actually became visible - too much - too late as it turned out.
PS Incidentally, I run a desktop Windows 10 box at this desk and all links have been present for the duration of the thread - confirmed on Firefox, Edge, Chrome and Vivaldi browsers - strange.