#4. The Saudi Arabian officials wanted it
With the kind of money that Saudi Arabia is pumping into the show, they seem to believe that they can basically get whoever they want, especially nostalgia acts. The word is that some officials demanded Yokozuna for the Greatest Royal Rumble without realizing that he passed away shy of two decades ago.
The biggest case and point about them buying legends back in to the ring is Shawn Michaels. He was reportedly offered a sum of $3 million just to compete in the main event of Crown Jewel. Imagine that - Shawn Michaels, the man who had adamantly stayed retired for over 8 years, was pressured into coming out of retirement for big money.
Ultimately, Michaels stated that he would never do it again, but the point is that WWE will go out of their way to pursue legends to return for the kind of money that the Saudi Arabia deal offers.