"This is freedom."
Bull. Because if a cab driver was to say that they refused to carry patrons for any of a variety of other reasons - skin colour, religious garb, gender, and so on - it would be called illegal discrimination. Personally, if I was in charge of permits for airport taxi drivers, I would tell them they can either take any reasonable fare (refusing to take a visibly drunk and vomiting person would be reasonable, for example) that shows up at the curb, or not work the airport at all.
OK, then ban them from working at the airport. What's the problem?