The ultimate disgrace in the stoning of the couple is not the act of adultery. Rather, it is the rule of the Taliban. There is much in way of hypocrisy that is shown. The players have to play soccer in long pants, while the Taliban official who is stoning the couple to death is wearing "John Lennon style sunglasses," a reflection of Western fashion by a member of a supposedly traditionalist regime. Additionally, Assef is the official who is stoning the couple for their sins. Yet, Assef is probably the most impure character in the novel, embodying how the individuals in the position of power are not worthy of their position and abusing it:
Assef, Hassan's rapist and the bully who becomes a high-ranking Taliban official, embodies the consequences of the abuse of power for power's sake and the violence and repression of the Taliban regime. Assef is a sociopath who thrives in an atmosphere of chaos and subjugation.
It becomes a very fitting statement that the most impure of characters is speaking about "purity" of the couple in stoning them to death. Hosseini does an excellent job of making the case that the Taliban should be one of the last people to speak of impurity and transgression with all that has been done on their watch.