The "pride in appearance" thing relates to beards, not dresses. And I do not consider it bigotry to demand professionalism. Can a female air hostess wear jeans and a band t-shirt? No. Is that bigotry? Of course not. So why should trannies be allowed to wear what an employer deems inappropriate clothing at work?

Being a transvestite is not unprofessional, no more than being a goth isn't unprofessional. Dressing inappropriately for work is unprofessional.