What country the commenter belongs to isn't relevant because the issue is how readers will react. Most won't react, but somewhere down the long tail there's a segment of readers who will become provoked and rush to the comments to attack back. Then we end up in flamewar hell. The only solution is not to go down that spiral in the first place, much as the only way to avoid a black hole is to steer clear of it.

Being right isn't relevant either, for two reasons: first, it's a category error to call pejorative language (e.g. "insane $country obsession", "bizarre and absurd") right or wrong, because it's emotional language, not propositional language. Second, again, the issue is the effect on the threads. Even if a pejorative provocation is 100% right in propositional content, not everyone will agree with it—indeed everyone feels it is they who are right—so rightness doesn't change the flamewar dynamic I described in the first paragraph. If anything, it makes it worse.

For avoiding flamewars, the issue isn't whether you're right or not, it's how you express your rightness and whether it's a good moment to make that point. If you're introducing or fueling a classic flamewar topic that's tangential to the topic at hand, it's probably best just not to, no matter how right you are or feel you are.

All of that is what's behind this site guideline: "Eschew flamebait. Avoid generic tangents." - https://news.ycombinator.com/newsguidelines.html