But not limited to" is within the scope of Force Majeur. It is not a Carte Blanche for the airline to do whatever it wants with no legal recourse. Otherwise they would not spend time and effort to outline the rules. They could simply say, "we have the right to refuse a passenger at any time with no reason" PERIOD, But of course that would not be allowed by the authorities.
FFS know what the definition of Force Majeur is.
Force Majeur are acts of God, so unless God himself wanted those four crews to travel ISO of the passenger, I am afraid United doesn't have a leg to stand on.
Force majeure (/ˌfɔːrs/ fors, /ˌfɔərs mɑːˈʒɜːr/ mah-zhur, or /məˈʒɜːr/ mə-zhur; French pronunciation: [fɔʁs maʒœʁ]) – or vis major (Latin) – meaning "superior force", also known as cas fortuit (French) or casus fortuitus (Latin) "chance occurrence, unavoidable accident",[1] is a common clause in contracts that essentially frees both parties from liability or obligation when an extraordinary event or circumstance beyond the control of the parties, such as a war, strike, riot, crime, or an event described by the legal term act of God (hurricane, flood, earthquake, volcanic eruption, etc.), prevents one or both parties from fulfilling their obligations under the contract.
NO they do not have the right to deplane for ANY REASON, and soon you will find out.
Sorry but you are really out to lunch.