The ruling on one who recovers from his illness after a proxy has performed Hajj on his behalf

Your Eminence, Shaykh Abdulaziz! This is a letter from its sender, Rashid Muhammad al-Rashid, from Dammam in the Eastern Region:
If the excused person recovers after his proxy has entered the state of ihram for Hajj, does the Hajj count as fulfilling the obligation of Islam for him, or is it a voluntary act in his case?
Answer: In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, and may peace and blessings be upon the Messenger of Allah, and upon his family and his companions, and whoever follows his guidance.
As for what follows: If the excused person recovers from the condition that justified a proxy performing Hajj on his behalf, the scholars (may Allah have mercy on them) differed: Does that Hajj suffice for the excused person, or must he perform it himself because the excuse has been removed? There are two well-known positions among the scholars of knowledge. The most cautious course for the believer in such a case is to perform the Hajj; because the majority of scholars hold that he must perform the Hajj; because it became clear that his excuse was not one from which recovery was hopeless, nor was it hopeless that it would end. The original basis for permitting a proxy to act on one's behalf is that the excuse appears to be one from which recovery is hopeless, like an old man who has no hope of returning to youth; therefore, it was permissible for a proxy to act on his behalf. So this excused person, whose excuse has been removed and whose illness was not one from which recovery was hopeless, should perform the Hajj like the other Muslims who have no excuse. This is the most cautious course for him, and it allows him to avoid the disagreement among scholars, and it follows the opinion of the majority. And Allah the Exalted knows best. Yes.