An argument over face masks turned physical on an Allegiant Airlines flight from Mesa, Ariz., to Provo, Utah, on Saturday. A passenger on the flight was wearing a face shield and a flight attendant asked him to wear a face mask as well, KSL TV reported. Allegiant’s policy is that face shields must be worn in addition to a face covering, not as an alternative. When the flight attendant and passenger were arguing about the policy, another passenger heckled the man, KSL reported. As the flight attendant was attempting to escort the passenger who refused to wear a face mask...