On July 1, 1972, and thereafter all persons who first enter employment in the San Francisco Unified School District or the San Francisco Community College District to perform creditable service subject to coverage under the Defined Benefit Program are members of the plan in accordance with Section 22501. These new members are excluded from coverage under Subchapter II (commencing with Section 401) of Chapter 7 of Title 42 of the United States Code, for service performed as a member of the plan.