I’m pretty sure them using Shaw when for unmasked Vader is because he was a seasoned actor who turned in an amazing performance. Prowse was a body actor. Look at his filmography on Wikipedia. I’m not really sure why he was so upset or what he was expecting. Playing tall imposing monsters was basically his thing.
Not saying that in a derogatory way at all. The body acting for Vader by Prowse is masterful. But that’s what Prowse was.
I not a huge fan of the prequals, but coming to accept them more since kenobi tie-ins and Hall9000 edits. I actually like this idea for the vader un-masking. and I never thought I would say that (also nice to see it released in HD or scaled). needs some sharpening on the eyes and maybe some fix on the skin under the eyes (compositing), but I like the effort here…still not sure hot it should end with the ghost and was going to go shaw in my extended version, which still might work since he doesn’t speak. I think shaws acting is good and that would still remain.