Has nothing to do with age Seaoat. It has everything to do with fitness and wellness.
Your point is well taken, but a man 48 years of age participating in the vigors of athletic competition, or fire rescue are at a much higher risk for cardiac problems than a 28 year old man or woman. In the same token the courts have always enforced mandatory retirement for some professions based on those same probabilities and the need for employees to be able to perform their job.
There is a reason that 48 year olds do not play in the NBA, and 70 year olds do not pilot commercial air lines.....it is called probabilities.....yes, a 48 year old man can be more fit than a 30 year old, and yes a 70 year old pilot can be more capable than a 40 year old, but the probabilities and practical experience are not able to support that conclusion.