You can imagine the problem, can't you? Someone of apparent middle eastern origin, on a flight in the US, speaking little or no English, quite possibly little or no experience of being a pax, finds their allocated seat occupied, and can't sit down. Quite possibly can't easily communicate with any cabin crew,(who are all harassed and pushed for time anyway) and gets thrown off. Misses connecting international flight as a result.......the lawyers will be round as fast as pilots offered free beer!
We had the thread the other day of the guy refused the flight on United. Especially with largeish companies, that sort of thing could lose an airline the total business of a multi national company - and in the current climate, no airline can afford that.
Doubtless the head office will hold the flight crew responsible whatever happens...