All membership contracts issued by the corporations shall contain a provision, to be first approved by the Commissioner, which shall permit the person with whom made and all persons entitled to hospital service under the contract, to receive hospitalization either in ordinary or in emergency cases, at any nonparticipating licensed general medical hospital selected by such person; and the hospital shall be paid by the corporation a charge or rate for hospital service, not to exceed the rate provided for in contracts of the hospital service corporation for nonparticipating hospitals. This Code section shall not restrict the right of the corporations, in their discretion, to extend this same rate to persons entitled to hospital service in nonparticipating hospitals other than general medical hospitals.