Here is Airbnb's discrimination policy: https://www.airbnb.com/help/article/1405/airbnb-s-nondiscrimination-policy--our-commitment-to-inclus....
The short answer is that hosts may not discriminate based on nationality. Gender is OK if the rental is a room within a home of the same gender living there. For instance a female host renting a room in her home can specify only females.
The long answer is more complicated. In some cultures there are problems that can arise due to booking certain other nationalities. There is a Korean host here who advertises foreign only and it is because if he allows locals then he gets an entirely different group of people who are not vacationers at all, but locals from his own city needing temporary housing, not what we would consider as Airbnb guests.
In my opinion (and that is all it is worth) a non-discrimination policy is not worth the paper it is written on. There are just too many variations of potential discrimination being espoused today under the false pretense of "inclusion." Yet the same people who scream about being discriminated against seem to be the first people in line to prevent people whom they disagree with from doing whatever it is the inclusionist does not like.
To me, money is green no matter whose pocket it comes out of. As long as a guest gives me the same respect for my beliefs that Airbnb says that I have to have for theirs then all is good. Personally I am more concerned about providing every travellor with an exceptional experience. I have had to make some modifications for certain nationalities (like one muslim couple who refused to use a comforter that had been used by a non-muslim) but I make modifications for people with allergies too.
OK, I'll get off my soapbox now... Probably did not answer your question anyway!
