70 is the new 50? There's a lot of good blokes out there who are too old for command. They carry years of experience and many of them could show the youngsters a thing or two in the gym. Cut off at 70? I can hear the snarls from here.
Maybe getting a bit past it now, but not so long ago I lost my Class 1 physical medical status but didn't lose my brain, so whereas I could no longer instruct ab initio pre-solo students - in case I should unfortunately die before they had proved that they could fly solo - but once they had gained a very basic PPL and could carry a passenger then I could have used my experience to help them towards the CPL and/or Instrument Rating, e.g. they could have built hours as P.i.C, with me just a passenger giving them very valuable hints, tips, and advice, i.e.. my instructing capability had no relevance to my physical medical condition ( or lack of it in fact ) but .... shock ! Horror! the very thought of it proved a non-starter to the bureaucrats, tho' I have sat as "Safety Pilot" for those cleared for solo Instrument Practice, and my unofficial inputs have been much appreciated.
In fact, NZ medical standards for a Microlight are set at the aged driver licence renewal standard, viz. at age 80+, whereas I can no longer renew my professional flying licence I am ( so far ) allowed to drive home after each driving licence renewal medical, so I can fly, and instruct on, a microlight. So all is not lost, we have had young students starting on the microlight - Light Sport Aircraft in some administrations - who have gone on to the Airlines or Air Force quite successfully.