When I started out in commercial aviation in my mid-20s I had the privilege of flying with guys that were approaching 60. These guys were knowledgeable, cool characters who were completely unfazed by anything thrown at them. It taught me the value of experience.
Agree 100%. In my airline the more senior guys also have the confidence and experience to, where possible, allow their F/Os' more time and space to make our own mistakes ( a/c handling or otherwise) and learn from them. I couldn't care less how old the boss is, if the respective airline and the authority consider them fit for the job then carry on regardless.
If a guy has the enthusiasm and desire to continue in the job 'till 70 and can pass a medical then where is the problem. As for a longer wait for command, well I'm happy to wait my turn. It's not like a command is a birth right anyway...