A recipient is permitted to take an action otherwise prohibited by § 35.10 , if that action is based on a factor other than age, even though the action may have a disproportionate effect on persons of different ages. An action is based on a factor other than age only if the factor bears a direct and substantial relationship to the normal operation of the program or activity or to the achievement of a statutory objective.
29 C.F.R. §35.13