Having flown the Puma for three tours, I would say that this was an accident that could have happened in any type of helicopter.
"Brownout" i.e. loss of visual references due to the downwash lifting the dust is a known hazard when operating in a dry environment like this but operational risks do have to be taken.
It's easy for the coroner to criticise the pilot from a non-expert point of view, but even a successful desert landing is only a couple of seconds from brownout, as the downwash catches up with the airframe. If the aircraft can't immediately be landed at zero speed, e.g due to uneven ground, it's all too easy for this to occur.