> Warning customers that your food is spicy is one thing. Refusing to accept that your culture isn't the only one on the planet that enjoys spicy food is something else entirely

Different peppers contain various combinations of different capsaicinoids, and spicy dishes fun different cultures also have different non-capsaicinoids as best components. It's very common for someone used to spicy dishes of one culture to not be able to handle those of a different culture, and I'm not at all surprised that people working in food have developed a fair skepticism of people who think (often not inaccurately, for some particular cultural cuisine) they can handle spice (and often food-culture-specific codes that bypass this skepticism by signaling familiarity with the food culture in question.)