Does rising to relieve oneself, then returning and performing ablution, nullify the reward of sitting after Fajr prayer (the reward of a complete Hajj and Umrah)?

This reward mentioned in the Hadith ( "Whoever prays Fajr in congregation, then sits remembering Allah until the sun rises, then prays two rak'ahs, will have a reward like that of a complete, complete Hajj and 'Umrah") is conditional on several matters, and will not be attained except by their occurrence:

Firstly: Praying Fajr in congregation. Secondly: Sitting in the prayer area (which is the entire mosque) until the sun rises. If one leaves the prayer area, even for an excuse, they will still receive the reward due to their intention. Thirdly: Praying two rak'ahs after the sun has risen. Standing up to relieve oneself will cause one to miss this reward, unless there was an intention along with an excuse.