Was the brother right in his decision to immediately expel the young man from his home after discovering that he was taking drugs?

The homeowner must admonish the young drug addict, instill in him the fear of Allah, remind him of the impermissibility of his act, and command him to repent. He may then desist from his error, and the homeowner will receive the reward for guiding him. He must also conceal his faults and not expose him, for the Prophet, peace and blessings be upon him, said: "Whoever conceals [the fault of] a Muslim, Allah will conceal his fault on the Day of Resurrection."