Estimand when treatment delays disease onset

I maybe misunderstanding estimands, but why would you change your estimand given the result? For Clostridium (I refuse to change the name) difficile colitis, physicians use a vancomycin taper in the hope of preventing recurrence. There is no evidence that the taper did so. I would both as a physician and potential patient consider this a failure. If anything, the taper has caused harm because it delays the offering of another hopefully more effective treatment.