Unificationism is very much concerned with justice in all its aspects, and how it might be achieved. Unification theory is based on a version of divine command theory, whereby God is understood as being inherently good and just, and goodness and justice in human affairs originates in God and in God's will or command.
Moreover, Unification theory is hierarchical—God is above humans, parents are above children, the leader is above followers, etc.—in its social and political ideals, and sees such hierarchies as inherently necessary and just. It also sees family organization as based on a structure between elders and younger people, between husband and wife, between parents and children, and so on, and sees preserving those relationships as part of justice.
Unification theory also attempts to hold that the family is the pattern for larger social organizations, so justice in family relationships is isomorphic with, or is the pattern for, justice in larger social relations. Whether that is really correct—whether larger human social structures should be understood on the basis of family structures—is a topic for further investigation.
Whether Unification theory is refuted by the criticism leveled at divine command theories is also a topic for further investigation.