#2 To show him being unaffected after that Hell in a Cell war
As mentioned in the opening slide, it was not just Bray Wyatt but also the Universal Champion Seth Rollins who didn't show up on RAW. As very well put by Riju in his analysis of the same, the reason could have been to sell the gruesome war that they had inside the Hell in a Cell.
While we all saw Seth Rollins bleeding heavily from his mouth after the post-match Mandible Claw applied by The Fiend on him, Wyatt himself suffered a merciless beat down at the hands of the Beastslayer inside the deadly structure. How can you be unaffected after almost a dozen stomps, chair and ladder shots to head, not to mention the sledgehammer shot that ultimately caused the referee to stop the match? It was a beating bad enough to get the ref to call a Hell in a Cell match.
A female WWE star said her life is in danger. Details HERE
Well, The Fiend making an appearance tonight could have been a way to put out a statement that he was unaffected, even after that vicious attack inside the Hell in a Cell, unlike Rollins who probably was in no condition to return to the ring immediately after that encounter.
The Fiend has been booked as one of the most powerful characters in recent memory. The question is - how do you stop this demonic entity from running wild through the entire roster?