(I'm not sure what "meant to be consumed primarily in the US" even means; I don't have national borders in mind when writing. For most sites it makes very little difference which country a visitor happens to be from.)
What would not make sense is to have a UK flag for American customers, a Spanish flag for Mexican customers, and the Democratic Republic of the Congo flag for French, just to appease people who will never buy from my site. You might not have national borders in mind, but it pays to know what language your customers speak as well as what countries they are from.
[1] http://thecultureur.com/wp-content/uploads/2012/12/e7qd6.jpg
However I can forgive the use of the American glaf in your example as if you're shipping software then that's a little different as it's a targeted application rather than my example example of a public facing website which would have people from all nationalities visiting.
Not everyone in the US speaks English as a primary language.
However, to get back to my original point, I was commenting about how all countries nationalise common language; and regardless of the justification of using an American flag for English language options, it's still an example of that point.
A lot of the examples in the article you linked to makes complete sense too. In most of those cases the nouns are what's been translated and the proper nouns have been largely left in English; as far as I know, that's how languages normally work. That said, I don't see the point to the governments alternative word for e-mail.