#1 A booking strategy to convince Lesnar to appear at Super ShowDown
Brock Lesnar winning the Money in the Bank might just be a negotiating tactic to make him work at Saudi Arabia. It was reported that Lesnar was a bit unsatisfied over the result of his WrestleMania 35 match and left the show early.
Despite the money, Lesnar would actually want the company to feature him in a way that improves his brand value. Getting defeated by Rollins in a non-main event and in a very humiliating manner actually takes a lot of credibility away from the Beast.
Thus, he might not be willing to come back unless they compensate for the loss from an on-screen perspective. If rumors are to be believed, then Brock Lesnar is facing Rollins at the Saudi show. Handing over the briefcase to Lesnar and having him challenge Seth is the only way to convince him if he is booked to lose again.