if a college that gives preferential treatment to blacks in admission is not racist because there is no implication of racial superiority, only that unequal treatment due to policies in the past have disadvantaged blacks. It is unequal treatment but it is not racist.
If that was true, colleges would not have given preferential treatment to all members of a racial group. If one believes that being black, in itself, is a disadvantage, this is a belief in racial inferiority.