If a passenger doesn't want to fly with a woman pilot then that is THEIR problem, not the airline's. Personally I would be very happy for them to not get on the flight and pay for a different flight. As for demanding to be put on another flight, well the answer is simple, this crew are fully licenced and experienced and the aircraft is serviceable. The service is operating and if you have a problem with that then go pay for another flight. Why should the airline side with that ignorant passenger? I don't think its even remotely a problem for airlines. Airlines also see women pilots as a good excuse for some
PR. There is still crap even now about "the first all female crew" and the like, whereas in reality its been going on for years.
I often fly all female crew and we always get plenty of comments at the beginning and then, when the flight is actually very good, we get patronising comments at the end like "well done for getting us here" and things like that, as if its quite amazing that we completed the flight safely.