The problem I see with that is that it still imposes extra logistics and restrictions on the airline. They have to work around her to make sure that there are enough people on each flight to serve alcohol. It works for one person, perhaps, but the precedent it sets doesn't work in greater numbers. Even with one teetotaler, they lose a versatility they'd otherwise have, and I think it's a versatility that's very reasonable for them to expect from their employees.