As for why Goldberg was chosen as Drew’s opponent for the show, this was addressed recently on Wrestling Observer Radio. It appears the decision to have Goldberg face McIntyre on the PPV was only made over the weekend.
“Bill Goldberg and Drew McIntyre is going to be the main event at the Royal Rumble,” Dave Meltzer said on the show. “This was decided on Saturday.” He continued to say that the angle seemed to come out of nowhere.
“It wasn’t a swerve, it wasn’t to throw people off, it was because they have nobody ready for anything.”
“The Goldberg decision was made on Saturday,” Meltzer continued. “So if you’re wondering why, you know, it just feels like this came out of nowhere, that is the reason, it came out of nowhere.”
The match against Goldberg will be McIntyre’s 3rd title defence in his current reign. He defeated Keith Lee last night and both AJ Styles and the Miz in a triple threat match at TLC. McIntyre successfully defended the WWE title 8x in his first run with the belt.