It would seem that the pilot has done a damn fine job in the circumstances if indeed the man (even elderly) was actually intent on disrupting the flight.
The fact that the pax appears to be injured and the plane came down off field would indicate pilot was seriously struggling.
It would be very hard to fight off a surprise attack from a seat next to you, let alone continue to fly a disabled aircraft.
Hats off to the pilot in what would have probably been a seriously frightening incident. Poor bugger.