LoL. It's actually been thought out years before UA. The Lead flight attendant sits in the front because they need to be sure the main boarding door is closed, they are within access to the flight deck for boarding, and their assigned exit in an emergency door is up front. Then, depending on the plane, one of the two F/As working up front actually IS up front on the jumpseat. The other F/A working up front is always in the back due to their assigned exit being in the rear of the aircraft.