This brother and sister duo is a lot like the Garners; they're the "safe," "good" white folks in Beloved. They do have one up on the Garners, though; the Bodwins actually walk the walk when it comes to helping slaves to freedom.
They do whatever they can to aid runaway slaves, including letting Baby Suggs her live in their house on Bluestone Road. All she has to do is wash and mend clothes for them—not a bad exchange. In fact, the Bodwins were once active abolitionists (26.260), and Miss Bodwin, by the end of the book, is teaching Denver and encouraging her to go to college (27.266).
But that doesn't mean the Bodwins fit in perfectly with the free black community they've helped foster. They're a little like Baby Suggs and Denver—fringe characters of the community who are just a little… weird.
Think about it, they're and unmarried brother and sister living together. Plus, they're white in a town of black people. Sure, all the African Americans in town probably owe a little of their freedom to the Bodwins, but there's still a distance between the Bodwins and the black people they've helped.
Why? Probably because the Bodwins are viewed as employers and homeowners: two things most of the black people in town aren't. They might be nice and all, but they still have the power to sell 124, which, by the end of the novel, they plan to do (27.264).
And, as Janey reminds us, if anything happens to the Bodwins, there go Janey's and Denver's jobs (27.264). The Bodwins may be a force for good, but that doesn't mean they'd be welcome in any of the black households in town.