Where a petition is filed for the appointment of a guardian for a mentally incompetent ward, a certificate of the Administrator or his duly authorized representative, that such person has been rated incompetent by the veterans administration on examination in accordance with the laws and regulations governing such Veterans' Administration and that the appointment of a guardian is a condition precedent to the payment of any monies due such ward by the Veterans' Administration, shall be prima facie evidence of the necessity for such appointment.