My gut feeling is that throwing a prop blade should NOT be able to generate enough force to shear a strut and cause the rest of that damage. Just as a matter of physics.
And, if a blade was thrown "totally and immediately" clear by a complete (rather than gradual) failure of the pin holding it in, I would expect the flowing water and forces on it to throw it well aft before it impacted. Seeing it directly above the normal position makes me think it was still on the shaft when it hit.
Which lead to me wonder, since the boat was HAULED two months ago, perhaps the problem is that the slings were misplaced, something caught on the shaft, and snapped or damaged the strut at that time. Now, two months later, the strut finally failed as a result of a slightly bent shaft or simply two months of the damage going further.
There are folks who can examine the damage at the prop and the strut, and tell from the physical properties of the breaks how they happened. Might be worth taking a close look at that strut, to see if it was stressed during the haul.