I'm no FAR scholar, but if they aren't US Part 121, I don't think we have a place to say at what age a pilot can land. Pilots over 60 land planes all the time in this country, just not ones who are operating under Part 121. Actually, come to think of it, I know a guy who flew for Jalways who was landing DC-10s willy-nilly in this country at age 63.