Is he actually an illegal? California is loaded with Mexicans who are US citizens.
Given that this restaurant is behind security it would take some seriously good forged papers to pass the federal level background checks to work inside the secure area of an airport. You would then have to pass security daily with proper identification just to get to work. The odds of this person being a illegal immigrant is virtually zero, given that ginger prints are required for the background checks to work on federal airport jurisdiction.
So what is likely is some racist couple couldn’t tell the difference from a legal resident or even a multi generational Hispanic in California where seven plus generation families exist in quantity. Same for Texas we have Hispanics here that predate the USA, Mexico even the Spanish Empire as they are indigenous peoples here since at least the last ice age. Latinos ARE indigenous people most are at least half if not 70+% by DNA native Americans or First Nation’s the difference is semantics the DNA between ,First Nations, Native Americans and Indigenous Americans is all nearly identical especially the Y chromosome group that defines the whole group.