State Regulatory Authority jurisdiction over an RUS borrower's rates shall be pre-empted by the RE Act and RUS shall have exclusive jurisdiction over the borrower's rates:
(a) On October 19, 1990, with respect to any borrower by or against whom a case under the Bankruptcy Code of 1978, as amended, was commenced prior to and remains outstanding on October 19, 1990; and
(b) With respect to all other borrowers, upon the filing of a petition by or against the borrower commencing a case under the Bankruptcy Code of 1978, as amended.