Marty. I received lots of letters prior to any flight training, from many airlines on the age issue. They all said that they did not discriminate on age. (they are not going to admit it are they!!!!). Then when i came to get a job, people with less experience, worse grades etc were getting interviews with these airlines but i was not, i drew the conclusion that they were discriminating on age!
I am also not sure if the stats show that older people have a lower % of passing courses, it may or may not be true. But you would have to take in mind the individual. Many older people tend to have a wife and children, these can be very demanding and take up a lot of time. They can also be unfitter (its a longer time period since school PE lessons and football on the field). If they have not continued any professional study then it will also be longer since they have done any exams.
The airlines should look at these points and make an assessment. Many of us older people are single, and physically and mentally fit and can demonstrate this. I know airlines dont look at these points hence I call them prehistoric!