I love language-learning, and I can usually bootstrap myself to a level where the locals don’t reply in English when I want to practice. However, with Dutch I found it difficult to bootstrap and I experienced what your Chilean did. When I complained about how locals weren’t letting me practice, I was told (the famous Dutch directness!) that I needed to simply hire a teacher to get to a higher level, instead of being annoying to local people. People’s time is precious, and a foreigner speaking the local language haltingly is arguably disrespectful of their time.
My experience mirrors what is described in the article, but only with people from Europe. Non-native English speakers from Europe look down on Americans, in a sort of "gate-keeping" manner where Europeans "own" the language. They have a better grasp of the "precise and elaborate formal English" and do not hesitate to correct Americans and tell them they don't understand grammar and are uneducated. (I'm inclined to agree with them.)
My experience speaking with non-native speakers from Asia, India, and Central & South America has been different. Maybe we are more willing to accept that there is a language barrier, but no one "owns" it.
And, like the article says, trying to use a culturally relevant idiom is a futile task.
This is a common pattern of false equivalency, like "reverse racism" and the likes.
The analogy is invalid because the harms of discrimination come from the power imbalance.
In this case, immigrants in the US are in a position of disadvantage, due to linguistic/cultural struggles and the perception issues they cause. Perpetuating stereotypes that reinforce that perception causes harm.
I'm not American but I don't like this. If an American author had written that everything is fine until "a foreigner joins the group" there would be a twitterstorm.
What's more, this is not about Americans, or even native English speakers. I'll give you a completely different example of how a group with a common language can exclude someone who doesn't quite share it.
I knew a couple were the woman was Greek and the man was from Chile. They lived in Greece and hung out with Greeks. I witnessed first hand, dozens of times, how the Chilean guy was left out of conversations. It happened in three phases. In the first phase, everyone would speak to him in English. This lasted for a few minutes, time enough to exchange greetings and pleasantries and so on. In the second phase, the Greeks would revert to speaking to each other in Greek. In the third stage, the Chilean man would try to join the conversation in Greek. At that point, the Greeks would reply in English. Then the process looped back to the second phase.
The Chilean guy was trying to learn Greek, but he never could - because nobody spoke to him in Greek long enough for him to learn it. He also failed to make any friends, because everyone spoke to him only for a short time, as long as they felt comfortable speaking in English.
Obviously I noticed this so I tried to rectify it by speaking to him only in Greek. We ended up code-switching a lot but at least we could keep going for a longer time than he did with others. I realised his frustration when we explicitly discussed how I spoke to him in Greek and he said, exasperated "you're the only one!".
Language can be a huge barrier that we raise subconsiously around us- but it doesn't help to single out one nationality for it. Everyone does it.