Injuries can happen at any time inside the squared circle. Owing to injuries, plans have to be changed on the spot and it seems that might have happened with Braun Strowman.
The company initially had plans for Braun Strowman to face Drew McIntyre for the WWE Championship at WWE TLC in December. It seems there was a good reason behind him not being included in the #1 contender triple threat match.
On Wrestling Observer Radio, Dave Meltzer noted that he heard Braun Strowman might have suffered an injury. This might explain why he was written out of action this week on RAW. The company made him headbutt Adam Pearce as a way to remove him from WWE television.
It was said that it is believed backstage that Strowman might have suffered a knee injury at Survivor Series in that elimination match.