I also have a "special needs" hen who gets bullied. Her sisters excluded her as chicks because she was clearly different - slight leg impairment, delays in feathering, kind of goofy and infantile behavior. I let the flock backyard free range, and she generally forages by herself, sometimes hangs distantly from the flock, or hangs out by the rooster who is in a kennel - they are friends. I will probably rehome the rooster and worry about her, but I figure it's better for her to have run of the yard with the distant social interactions, and I use multiple feeding stations and scattered treats.
I actually would love to rehome her with the rooster because she makes incredibly loud yelling noises early in the a.m.!! But I think that would be too harsh of a transition for her, unless it was a very special situation, such as with younger, newly introduced pullets where she might be able to establish some status. So I will probably have to continue dealing with the noise...