Is it permissible for a man to boycott his sister, who insisted on marrying a man who drinks alcohol, with the aim of deterring her husband from drinking alcohol?

Drinking alcohol is one of the major sins, and it is permissible to ostracize the one who drinks it if it is highly probable that it will deter them. As for the wife who does not participate in the sin with him, it is not permissible to ostracize her, and ostracizing her is considered one of the major sins because it severs kinship ties. The fact that she married without the brother's consent does not justify cutting ties with her if her closest guardian approved.