Not sure what limit you are asking about. However a commercial pilot called Ian Evans took on the CAA a decade ago because of restrictions automatically placed on him at 60. The evidence in court was accepted to show the risk of a pilot becoming incapacitated at 60 was less than the risk of a 50 year old only a generation ago. In other words we are now healthier, love longer, and medically safer.
Unfortunately the CAA won as the law states that they do not have to change the rules. They argued they didnt have the money needed to reassess the risk and therefore were going to stick with data from the 1960s.
I suspect therefore the answer is that in terms of risk any automatic limitations are now medically unjustified but the regulator is exempted in law from reviewing what may be out of date restrictions. If so you need a politician not a doctor to help you. And I would be surprised if any limitation based solely on age will be subject to a dispensation as if they give it to one person they open a can of worms at Strasbourg for all the other pilots whose human rights have been effected.