Actually Hooters did not lose the case. They settled to make it go away. The settlement allows Hooters to continue luring customers with an exclusively female staff of Hooters Girls.
The only change Hooters had to make was to create a few additional support jobs, such as bartenders and hosts, that must be filled without regard to gender. So in essense they won.
It was ruled tha under the bona-fide occupational qualification (BFOQ) exception, restaurants that market themselves as entertainment are allowed to discriminate on the basis of age, race, sex and other protected classifications. Similarly, film directors and amusement park operators are allowed to cast for certain types of people.