Maybe the finale was the point at which Gary and George could no longer protect Ben or overhype him, even they'd know that if he'd been judged the winner despite Sashi being way better, the backlash on social media would have been huge and the Masterchef brand would never have recovered.
I looked at that gantry last night and it was obvious that there were 4 people at least up there who have been better opponents for Sashi, Khahn or Reece especially were more consistently good over the season than Ben, who frankly was propelled along by the 3 judges all the way. Similarly, Sarah and Chloe were kept on the show for far longer than they should have been.
For 2019, Gary and George need to put into retirement, get 2 more impartial judges, and cut out some of the stupid immunity pin challenges too.