The ump didn't call it fair. He showed the safe sign to indicate that it hadn't touched the player or the bat. When the catcher played it, only then did he indicate fair.
It is easy if they have to consult, to change a fair call to foul. The opposite is the problem. I had a young ump in a mens league game call a ball foul halfway to the bag. Then it came back after my batter stopped.
It started FOUL BALL, followed by the ball in his estimation crossing the corner of the bag, IT'S FAIR. Their first baseman grabbed it and touched the bag for a last inning out. Those we have calling these games in the WCWS are way better than that. We'd all be the ones complaining, I suppose, if the same bunt had happened with less than 2 strikes, and the Duck catcher had made an accurate throw to first for the out.