Yes commercial airline pilots must retire at age 65 for safety reasons.
The retirement from commercial airlines as a pilot is mandatory and is by law so if you're an airline pilot with a commercial airline you must retire at age 65 regardless of health.
It's to ensure the safety of passengers because the older you get the more chance you have at possibly having a heart attack, other illness etc or even die while piloting the plane.
Even though just because you're 65 or older it doesn't mean you're gonna die or have a heart attack the possibility is there so they set that regulation in place for the safety of the passengers on the plane.
There's no negotiating it.
You can still however fly your own personal airplane if you want too at 65 and beyond but not commercial airlines.