Roman Reigns and Shayna Baszler were originally planned to be the winners of the Royal Rumble matches but Vince McMahon apparently changed his mind about a week before the show, Dave Meltzer of F4WOnline.com reports.
The belief is that Vince made the decision because he wants Brock Lesnar vs. Drew McIntyre for Wrestlemania 36 to be as strong of a main event as possible.
The original idea was that McIntyre wouldn’t need the Rumble win after eliminating Lesnar but Vince wanted to give McIntyre that extra push.