We have laws that prohibit discrimination against fags. Therefore, fags must be admitted. I should have been a little clearer in my initial post by adding, "unless there is a law that prohibits whatever condition a property owner would like to impose." Any such law must pass constitutional muster, of course. Usually, they are based on the equal protection clause. Unmasked persons are not members of a protected class so can legally be excluded from private property.
Ironically, there are laws in some areas that make it illegal to wear a face covering in public. So a business operating in such an area that requires a mask may be in violation.