The problem? Are you kidding me? If guys start dying on the road in hotel rooms or even in the cockpit, when their state of mind deteriorates to the point that they are more of a burden than any help, you don't think that poses a problem? I consider it a major safety issue, I have flown with some who need constant baby-sitting because they are too old to remember how to do anything correctly. I certainly know that during an emergency, they would be in over their heads....
It is even enough of a problem at NJA that the union and company are launching an aeromedical committee to help determine which pilots are fit and unfit for duty. I think that speaks volumes.
Just to clarify, I am not casting a negative light on all older pilots, but SOME just don't know when to quit.