We ABB a room in a 3bdrm apartment where we are not in residence and our listing is for Men Only since the other two LTRs are college boys. The 2 boys share a bathroom that's behind the kitchen which means they probably don't dress to use it in the middle of the night, especially when they often don't keep regular hours. It would have just been my luck to have a female guest in the kitchen when one of them paraded through in their skivvies. So even though that significantly narrows the market for us, it was just common sense. I also didn't want my LTRs feeling awkward in their home, nor put them at risk if a female made a claim or police report against them. As the Host, that would create more problems than I even want to think about!
So, I fully understand and support single hosts wanting to host same sex guests when they rent rooms or share space.