Pronouncing jalapeño wrong allows them to signal their belief in superiority of English and whiteness also. They would maybe be embarrassed mispronouncing things like Oakley's or Chevy Silverado.

the conservative coffee fantasy is rooted in the association of coffee with ruggedness

I agree with this, this is most of it. Another part is the general suspicion of outsiders and external ideas. To them, it’s just rebranded coffee, coffee being a famously cheap thing. They think that a latte is just an overpriced drip coffee, the same way many users here are suspicious of Apple selling overpriced computers. The more breathlessly you explain espresso to them, the more they think you are blowing smoke up their ass.

The desire to be a white boy with swag and correctly pronounce "jalapeño" vs the caucastic impulse to let 'er rip with "juhlapenno."

I'm not talking about pronunciation but rather what the drinks actually are. They still get that pang of anxiety when they have that first experience of asking for "large black coffee" when one is not on the menu, and they also get it because they know they don't know what the name is for that on the menu so they feel like they're exposed as frauds.