Jehovah's Witnesses were well behind the curve in the United States with respect to civil rights(Brown vs Department of Education, 1954). The concern was always "community standards," not Christian principles. Corpus Christi, TX was integrated in 1969. Little Rock, AR had a predominately black congregation that drew from all congregation territories in the city until 1986. Oh, there was a sprinkling of black publishers in all of the Kingdom Halls in Little Rock, but, the nearly all black congregation was tolerated and encouraged.
As for interracial marriage, that was tolerated with the understanding that opportunities for organizational advancement might be limited.
As for congregation responsibility, this was an area where non-whites could excel, giving an impression of even-handedness.
For some reason, while JW's taught that all races were brothers, they never wanted to make an issue of this in the community.