to revise the laws for the selective service to require woman to register for the selective service.

The supreme court has ruled that since woman were not allowed in direct combat roles, the law for the Selective Service was constitutional. The Department of Defense is removing the ban on woman in direct combat roles and there fore, the law needs to be revised to apply to woman as it does to men, otherwise, it is discriminatory.
Furthermore, even if woman were not allowed in direct combat roles, there are non-combat related roles that can be filled, just as being done in the Alternative Service provisioning for conscientious objectors.