What is the ruling on emigrating from Egypt if its people fight Muslims over a single brick, as mentioned in Sahih Muslim, and if the emigrant cannot find a Muslim country to go to?

As for the ruling on leaving Egypt upon witnessing conflict, it is specific to Abu Dharr, may Allah be pleased with him, and does not apply to all Muslims. This is for two reasons: 1. The departure of all Muslims from Egypt contradicts the objectives of Islam in spreading the religion and exalting the word of Allah, especially after they sacrificed so much to conquer it. 2. The majority of scholars believe that a discourse addressed to a specific individual (singular) does not include others in its ruling, unless a text or analogy indicates otherwise. In this hadith (definition), the command to treat the people of Egypt kindly came in the plural form, "treat them kindly" (fa-ahsinū), whereas the command to depart came in the singular form, "depart" (fakhruj).

Therefore, it appears that the Prophet's command to Abu Dharr to leave was specific to him. Perhaps it was guidance for him to leave when signs of tribulation appeared, or a prelude to what the Prophet (peace be upon him) had foretold: that Abu Dharr would die in a desolate land.