You can’t even just change to any open seat in economy anymore now that airlines sell some economy seats for extra money.
Self-upgrading to business class has never been considered okay. It also rarely ever works. I’ve seen people try it and they’re always sent back to coach. Usually they’re a bit sheepish as they head back, sometimes offering some innocent-sounding explanation about how they thought it was the same cabin (no they didn’t!) and the seat was empty.
Passengers who refuse to move get the David Dao treatment. In fact here’s video of another Asian passenger on United being dragged off of a Shanghai – Newark flight after trying to upgrade himself to business class several times and stealing champagne.
Today video came out of an American on a Korean Air flight being dragged out of business class after attempting to self-upgrade. When cabin crew try to get her to move, she chants “US marshal! US marshal!” as though that’s who she hopes responds. Then they try to move her and she laughs that she’s wearing a seat belt so it isn’t that easy.
She’s eventually dragged down the aisle — cabin crew may be small but I wouldn’t want to run into one of them in a dark alley — and she’s strapped into a chair to remove her from the aircraft. The woman yells something about the airline, perhaps confusing North and South Korea, and shouts “nuclear disarmament!”
It wasn’t just appropriate to remove her from the aircraft it was indeed imperative to do so on the ground or else they’d have been dealing with her in the air where she might have been judged a threat to others and forced a diversion.