Final answer:
The irony lies in the contrast between the idealized, strong image of Augustus depicted in sculpture and the reality of his physical ailment, where he lost his leg to bone cancer.
Step-by-step explanation:
The irony in the portrayal of Augustus standing in a contrapposto pose despite having lost his leg to bone cancer lies in the contrast between the idealized representation of the emperor as a perfect, able-bodied figure and the reality of his physical condition. Augustus was commonly depicted in statues in a way that emphasized his role as a strong and capable leader, much like the idealized figures of the Golden Age of ancient Greece.
However, the reality of his condition with bone cancer that resulted in the loss of his leg presents a stark contrast to the powerful and healthy image portrayed by the sculpture. Furthermore, the practice of representing leaders in an idealized form, regardless of their actual physical appearance or ailments, was a common tradition in Roman art, focused on symbolism over literal representation.