A policy shall not be issued by such association until membership in such number and with such numbers of employees as the Commissioner may decide will give a fair diffusion of risks shall have obligated themselves to take policies immediately upon their authorization, nor shall a policy be issued except such as the Commissioner shall have approved as conforming in all respects to the requirements of the law relating to such associations. If, at any time by the retirement of members, reduction of numbers of employees or other cause the membership of any association shall appear to the Commissioner no longer to afford a fair diffusion of risks, he or she may suspend or forbid the further issue of policies until the former conditions of the association have been restored.