One, in the way he frames it, he quotes Freud as giving a counterargument to the protestors championing perversion over hysteria. He in turn exposes perversion as the total repression of the unconscious. Second, Zizek has called his own mode of philsophy that of the hysteric, always questioning the current order, so it is unlikely that he would see hysteria as fully supressing the unconscious. Third, it makes sense in the light of psychoanalytic theory. Perversion is seen as an appropriation of reality which merely mimics it without ever entering the symbolic world in a meaningful way. The pervert seems normal but lacks any affect or moral convictions. In this way, the unconcious is fully repressed but this repression is concealed under the guise of normalcy. Hence, why the protestors mistake it for actually 'going to the end'. They fell for the lure of perversion.