Harris never wrote something as outstanding as this part of powerslave. Music theory wise, don't crucify me!
Look, I agree with your statement, and that's why I said that he found it by accident. I found this scale, thought it was cool, wrote a part using it, and Dickinson played around and found that riff that, by chance, belongs to this scale. Whatever works I guess.
*Actually that part in Rime after the solos is interesting. I might check it out later.