Discrimination and Who Discriminates

From a piece on a study of discrimination among Airbnb hosts:

They found remarkably consistent effects: The discrimination appeared to come from both black and white hosts, men and women, hosts renting entire properties and those sharing rooms in their homes. It came from hosts listing expensive properties as well as cheap ones. And the neighborhood didn't seem to matter either — hosts in diverse neighborhoods discriminated about as much as hosts in homogenous places.
There was one exception to this broad pattern: Black female hosts didn't appear to discriminate against black female guests.

I don't understand the exception: do black females share a feeling of sisterhood based on their race and gender--if so,why?  Is it an expectation based on church-going, that single ladies who are traveling are likely to be churchgoers and therefore okay?