THe only guys against it are the people who have not got commands yet and want the soon to be 60 people out so they can have their seat.
I have my command thank you very much and have no intention testing the advances of medical science by flying 900 hours a year until I am 65.
The facts are more people die suddenly in the 60-65 age group than the 55-60 age group. Throw in the small matter of the very stressful day we all experience occassionally and that cancels out any benefit gained from our frequent medicals.
No matter which vested interest study you wave about the odds of an incapacition are increased. Therefore safety is reduced.