Especially given than history is littered with examples of airplanes not being able to pull out of dives due to control surfaces not responding properly (or ripping off) in supersonic or transonic flow. Alsbury would have been intensely aware of these concepts.
Well it's not exactly like deploying flaps at high speed and having them rip off the plane and damaging stuff. He didn't deploy anything, he only unlocked it. He thought the motors would hold the feather in place and nobody at Virgin or Scaled drilled into his head that prematurely unlocking feather = DEATH. Quite possibly because they also didn't think the feather would move by itself just from air pressure and vibration. We know it NOW, but before?
Unlocking the feather while going up was part of the procedure. He did it too soon but was not adequately informed of the disastrous consequences of mistiming the unlock. So yeah, I do agree they're blaming the dead guy too much.
Also, Alsbury was an experienced pilot but not exactly a Chuck Yeager. As to whether pilots would think through all the possible consequences of every action in a cockpit jam packed with switches and levers and knobs, under a heavy workload, well it's easy to say while we're sitting in a desk but reality is not that sterile.
Keep in mind the SS1 was a scary ride and I assume SS2 is no cupcake either. When that rocket lights, it kicks your ass not just with monster acceleration but also crazy vibration and deafening noise. It scared Brian Binnie shitless and he was used to flying F-18s off carriers. Even Mike Melville who is about as cool a customer as they come (and an excellent, excellent pilot btw) was quite impressed shall we say. A good pilot would get used to it pretty quick I'm sure, after doing it a couple times. The first time? It would mentally compromise most anyone including experienced pilots and you'd have to have superhuman levels of the Right Stuff to function at 100% the first time you're on that crazy rocket ride.