age discrimination
It's a long time since I have had the misfortune to read such rubbish on this forum , as long as an instructor passes the check ride and medical why stop them instructing ?.
Some of the best instructors that it had ever been my fortune to meet are over the "normal" retirement age and bring with them a wealth of experience , I once had the pleasure (in the USA) of flying with a 79 year old Flight Engineer as the FAA don't put an age limit on Flight Engineers and one of the training Captain was well over 65 but he could only fly training flights as these are conducted under part 91. Both of these Gents were superb airmen and passed on to me much wisdom.
It was my impression that the first flying job that these guys had involved urban re-development in Japan.