Black members of the church didn't exist before 1978. If you had any African ancestry at all they wouldn't even teach you, you couldn't join at all, it was part of the missionary lessons, they asked you if you had any African heritage.
Sisko didn't have the privilege of being a peace time captain. He had to be at the center of a war between galaxies with everything at stake. He didn't have a choice how agents he may have protected acted. he didn't command, direct, or approve of their methods. He only benifited, and protected, with disgust and grief for the values he once held dear. But all he had then was the list of all those lost, and the precise knowledge that losing the war, ment total destruction to everything and everyone he cared about. It would be future generations that would judge him, no one who marched through the mud along side him would.
She was very interested in what data had to say though, she was more eager to learn by the end of it.