Let's keep in mind that no slots were going to be instantly gained by opening LGB to international flights. While allowing the FIS to be built would have signaled a willingness to allow an expansion of LGB slots, I'm guessing it won't have much of a short term impact on West Coast growth.
Like Flyby said, a longer term solution is needed. Could LGB still be that solution? The city owns the airport. If I remember correctly, the noise ordinance is exempted by the FAA. What if the FAA could be convinced to have a change of heart about the slot restrictions?
Going with the city council didn't work, but I'm guessing there are probably some other levers the company has to pull to help LGB grow.