First of all, let us try to be as charitable as we can. Nietzsche opens his rant with a disclaimer that these are his "truths." He has mocked "truth" from the start, and now he is finding what there is in himself to laugh about. Clearly, he himself acknowledges that his bias against women is unreasonable, and he has greater courage than most of us in being able to admit to his prejudices and even to laugh at them.
His discussion of truth and his blatant example of prejudice also highlight an interesting new twist to his perspectivism. It seems that, while Nietzsche lauds the ability to remain free-spirited and see matters from all sorts of different points of view, he is convinced that no one is totally free from being fixed in a certain perspective. In a sense, one of the virtues of digging deeply into oneself is to uncover one's own prejudices, one's own "truths," with as much clarity as possible.
Nietzsche's confession of his prejudice against women can also help us to highlight a more general weakness in his writing: he has a tendency to see people according to types. While his attitude toward the Jews is far more complex and admiring than anti-Semitic interpreters believe, Nietzsche does have a tendency to talk about "the Jews" as though what he says could possibly apply to all Jews. He generalizes about race a great deal, and this criticism could also be extended to Nietzsche's remarks about Christianity and democracy. Nietzsche tends to caricature his opponents, and while his criticisms are often viciously accurate, it is highly contestable that they apply to all Christians or all democrats. In fact, we could even use Nietzsche's own method, and suggest that stopping with "Christian" or "democrat" is like stopping with "pleasure" or "pain"; these generalizing titles obscure the more complex and subtle fact that, for example, all sorts of different people believe in democracy for all sorts of different reasons.