Yes, people can be removed from airplanes for being rude and/or threatening others. Airlines have strict policies and regulations to ensure the safety and well-being of all passengers and crew members. If a passenger's behavior is disruptive, disrespectful, or poses a threat to others, the airline and its crew have the authority to take appropriate action, which may include removing the offending passenger from the flight.
In such situations, flight attendants or other crew members will usually try to de-escalate the situation first by addressing the individual's behavior and requesting cooperation. If the passenger continues to be disruptive or poses a safety risk, the captain of the aircraft may decide to divert the flight to the nearest airport to have the unruly passenger removed from the plane. In some cases, the disruptive passenger may be met by law enforcement upon landing.
It's important to note that airline passengers are typically bound by a contract of carriage or set of rules established by the airline, and disruptive behavior can be considered a violation of these terms. Passengers are expected to adhere to these rules and show consideration for others during their air travel. If a passenger's behavior is deemed unacceptable, it can result in removal from the flight and possible legal consequences.