The statistical probability of two over-60's pilots becoming simultaneously incapacitated ( OK, within an hour or so ) is within the realms of the unlikely 10 X -14 probabilities used to predict catastrophic failure during a CAT 3 landing. We are still checked every 6 months and most of us who are still flying keep ourselves fitter than most 30 year olds. Not to mention that we don't get so stressed out, we've seen it before.
I see no logical reason to prevent 2 over 60's flying together, we jump through the same hoops to prove our flying ability as a 20 year old. Medical statistics do not prove that we are a bigger risk, so it is basically down to 'ageism'. I believe that this is now illegal, at least within the EU. Some people are surprised that we can use a computer!
I now only work because I enjoy what I do. My airline needs me, my licence and my experience. When they grow past that I will move on. I love my profession and it might take a missile to get me down from my place in the sky. I suspect that the ultimate ceiling at 65 will do it before that happens......