"If the pilot had selected some or full flap prior to or during the left turn, he would have been able to extend his glide distance further and reduce the aircraft’s stall speed, and potentially the aircraft’s speed at impact."
He is not saying that the glide angle is better with flaps down.
"However, given the location of the aircraft when he commenced the left turn, and the nature of the surrounding terrain, it is very unlikely that a collision with terrain could have been avoided."
So extending the glide is insignificant compared to stalling and hitting the ground hard.
"The aircraft was at about 60 ft (see GPS information) and had a groundspeed of about 124 kt (about 230 km/h)." .... "If full flap had been selected, the stall speeds would have been reduced by about 10 mph (9 kt) for the same bank angle." ... "Given the stall warning was intermittently sounding for the last 7 seconds, and the indicated airspeed decreased from 65 kt to 60 kt, it is very likely that the aircraft was close to the stall speed during this period. In the last 1–2 seconds, as the bank angle increased to about 60° and the indicated airspeed was about 60 kt, the aircraft may have entered the stall. The pilot’s use of left rudder in this period increased the potential to stall."
"All of the options were likely to result in at least some level of damage and/or injury. However, with the benefit of hindsight and a detailed consideration of all the available information, the option likely to result in the least damage or injury was to land the aircraft ahead on the remainder of the beach (heading north)." Hindsight is for us to learn from.
"Regardless of whether the aircraft stalled, the aircraft impacted terrain with little or no control and a significant descent rate." That is the thing to avoid.
Interesting that camera and camera memory disappeared.