He’s certainly free to try to run the hotel that way, but if the cats just won’t herd his way and he gets enough public grief then he may just have to cut his losses.
Taos (as well as many another charming spot in New Mexico, which some people famously do not believe is part of the USA) was Hispanic way before it was cool to be Hispanic. It is arguably an exception to the P.C. rule of reconquista.
Consider yourself challenged on that assertion. And I speak Spanish fluently. If most of the customers don't speak Spanish, the owner is in the best position to decide what works for his hotel. You want insults in a language you don't understand? Stay somewhere else.