Muta as Black Scorpion

You are correct, it would have been great. I can see how they might balk at someone without much in the way of English promo skills filling the role, however. However, the fact that someone who doesn't speak much English was cutting promos on Sting months earlier would seem to be the least of the plotholes anyway, so I think they should have done it. Plus he was there for the tag team tournament at Starrcade anyway! If he had a hole for his mouth in the mask, they could do the dramatic staredown and Scorpion would blow mist at Sting and then unmask for the big reveal.