(a) It is not a violation of this article for an employer to terminate, discharge, dismiss, demote or otherwise discipline an employee over 40 who fails to perform the normal functions of his or her position or who fails to conform to the bona fide requirements of his or her position, so long as the performance standards and job requirements do not discriminate against employees over 40.

(b) Where an employee is continuing in employment beyond his or her normal retirement date, it is not a violation of this article for an employer to terminate, force the retirement of, or otherwise discipline such an employee if the employee's job performance no longer satisfies the employer's performance standards. Any such performance standards for quality of work must not be arbitrary and must not be based upon the age of the employee.