Partial Source: Pwinsider
The script for this Monday’s RAW Supershow from Memphis was not finalized until around 8pm local time.
The angle with Kane coming from under the ring was written about a week ago but officials didn’t know how they would get to it until the day of the show. The six-man elimination match was put together at the last minute. They did the angle to provide a "safe but dangerous looking" cliffhanger for the Cena vs. Kane storyline. Due to the way the angle was done, that is why the six-man tag had to end the show.
Officials wanted John Cena in the closing segment so there would be an “Indiana Jones-like” cliffhanger to end the show. The feeling was that the CM Punk segment wouldn’t be exciting enough and Chris Jericho’s return wouldn’t be a good way to end the show.