WWE brought a massive show to Saudi Arabia and they wanted to make it as powerful as possible. The huge 50-man Greatest Royal Rumble match was just the icing on the cake for the Saudi fans and WWE wanted to make sure they got everything that they expected.
It was noted in the Wrestling Observer Newsletter that Vince McMahon was told that the Saudis wanted Yokozuna, The Ultimate Warrior, and The Undertaker on the show. Since The Deadman was the only person who was alive to make the show the thought is that this is why Sumi Hiroki made an appearance in place of the late-great Yokozuna.
Vince McMahon is said to have the idea that when going to foreign countries and doing media appearances that people want to be “in awe of great size.” This is why Mark Henry was not only chosen to go over early and do media appearances but why he was included in the match as well.