A reader makes a good point. I would like to think this is the correct and accurate interpretation:

Jonah – I am shocked you don’t consider Serena’s line a subtle mocking of the identiy politics on the left: We know nothing about Serena’s sexual preferences, and we have to assume that Fred Thompson also knows nothing (considering she shocked look on his face). Yet when Serena was fired for being a lousy DA, her first response was to assume it had something to do with her membership in an Opressed Minority Group.