I don't know you, so my observation did not include, nor does it rely on, any ideas about where you grew up or in which cultures you can seamlessly operate.
If that wasn't clear from the generic wording of my first comment, it should have been clear from the second, where I clarified this is an observation over many nationalities (unrelated to you and your declared identity), and that one contributor to this "offense gradient" could be that it is a reasonable reaction to discrimination faced as a minority.
The point is that I find it interesting how much the tendency to take offense over racial/national stereotypes varies by culture/language, and that the American/anglophone culture seems most likely to take (or worry about giving) offense. This is an observation independent of any judgement about the right level of offense.
(And while it would be interesting to further understand these cultural differences, my quip about a study was a mock-serious response to the parent's sarcasm.)