For someone who "has scrutinized the report in great detail" you seem to have missed that they do not state anywhere that CoG controls speed... However, they do note that trimming required a lot of revolutions of the trim wheel in an already high workload situation for an inexperienced pilot. Having jumpers sit far back in the cabin on the baggage shelf (where they were not allowed according to the AFM) would only exaggerate the change of CoG moving aft and resulting trim needed to maintain speed. They noted also it might take more time to trim then is available before dropping to or below stall speed. A more experienced pilot might act proactively and anticipate these changes, but we are dealing with a fresh pilot here.
Everything is connected as always. Blocking off the baggage shelf might have helped on this specific flight, preventing this specific accident. But it seems this was a bit of a lax operation anyway, and operating with some very small safety margins, likely due to lack of experience and skill of the person ultimately responsible, the PIC. So perhaps an accident would have happened at a later time still. But as always, this specific accident could very well have been stopped by removing one link of the chain such as the baggage shelf.
I also have some experience with the SHK people, and can tell you they are well informed, thorough and quite professional.