Maybe the airline shouldn’t be putting their employees in that position.
In what position? Enforcing what is effectively an attire rule they’ve clearly communicated to all customers?
The airline is not at fault for a violent criminal passenger physically threatening and attacking their employees over a dress code requirement. Would you also blame the airline if this person refused to wear pants and the employees were attacked when denying boarding over it?
American Airlines sets the rules for what goes on within their aircraft. If they’ve deemed masks a requirement to fly with them, then either follow the rule or don’t fly. You don’t get to just ignore their rules and make up your own, and you certainly don’t get to physically attack people because you disagree with a business’s rules.
Lock this criminal up and prosecute to the fullest extent of the law. One more violent maniac off the streets.