According to a report from PWInsider, AJ Styles was added to the 5/29 edition of RAW as a last second creative decision.
Further information seems to indicate the decision was a call by Vince McMahon, who has notably been making regular changes to WWE creative remotely.
As reported in our coverage of RAW that night, AJ appeared at RAW to give new WWE World Heavyweight Champion Seth “Freakin'” Rollins a show of respect, which was soon interrupted by the arrival of Judgment Day.
The group would go on to challenge Styles and Rollins to a tag match, which saw Styles and Rollins defeat Damian Priest and Finn Balor in the main event of the evening.