I've discussed the matter of aging pilots, with the MD who does my medicals, at some length.
This guy also does medicals for foreign carriers and is very involved in the aviation industry.
He's a firm believer in a fixed age and has told me the problems he faces trying to assess the mental conditon of old pilots during the time it takes for a medical, almost an impossible task.
On the only occasion he failed an elderly pilot, for confusion in his case, this individual promptly obtained his medical certificate elsewhere.
A couple of managers can't understand why they're hearing stories but haven't had any hard evidence like formal reports. You don't need to be Albert Einstein to work that one out.
The industry is relying on pilots to dob in their compatriots so you're leaving yourself wide open to allegations of harassment.
Better to leave the dirty work to someone else, right?