George Q. Cannon articulates the priesthood restriction.
George Q. Cannon, "Peace and Prosperity of the Saints," Journal of Discourses, 26 vols. (Liverpool: John Henry Smith, 1883), 23:105
It is a church that belongs to the whole people of the north and of the south, and there are no sectional heartburnings in our midst. God in his providence had made this a place of refuge from the north and from the south. They can come here without heartburnings and without prejudice; no civil broils, no disunion; they have nothing to remember or forget connected with us. It is a church that is adapted to all. The black man is welcome, and he is entitled to the rites of the Gospel, though the Lord has shown that to his race the Priesthood is forbidden.