If the restaurant requires a period or other theme costume, I would think that would fall under the category of something inherent to the job -- if you can't wear the prescribed uniform, you simply can't do the job. There was a case of a Sikh man who lost his discrimination lawsuit against Chevron, because his job required him to use a respirator and he could not put it on properly without shaving his religiously-required beard.
"If ye love wealth greater than liberty, the tranquility of servitude greater than the animating contest for freedom, go home from us in peace. We seek not your counsel, nor your arms. Crouch down and lick the hand that feeds you; May your chains set lightly upon you, and may posterity forget that ye were our countrymen." -- Samuel Adams