All revenues derived by the district from the operation of any revenue-producing facility other than revenues which may be required to discharge covenants made by it in issuing bonds, notes, or other obligations as authorized herein shall be held, disposed of, or expended by the board for purposes germane to the functions and purposes of the district. Any expenditure permitted by the provisions of this act pursuant to § 44-7-2157 to be made by or on behalf of a district is considered an expenditure of operating and maintaining public hospitals and public facilities for a public purpose and no expenditure permitted by this act or any other provisions of law may be considered to be a lending of credit or a granting of public money or a thing of value or an aid of any individual, association, or corporation within the meaning of any constitution or statutory provision.