You're dancing around it, and there are plausible alternate meanings for "cosmopolitans" and "postmodern cosmopolitans" and even, perhaps, "cosmopolitan intellectuals". But "rootless cosmopolitan" has an unambiguous antisemitic meaning.
For example, I didn't even think of it until you pointed it out. I disagree with a lot of the sentiment in Vektorceraptor's comments, but I immediately grasped their meaning behind "rootless cosmopolitan".
Maybe it's because I hail from the same region. I was born in what was Yugoslavia back then and is now Serbia, and I left when I was 20. I spent 14 years in South America, and another 10 here in the US, and I guess that makes me one of Vektorceraptor's "rootless cosmopolitans": someone who has been exposed to different cultures and can live in them, but doesn't really feel at home in any of them.
So no, "rootless cosmopolitan" might sound to you like a dog whistle for "Jew", but it doesn't have to mean that on a culturally diverse site like this one.
EDIT: It might be worth reflecting on the fact that English is not a native language for everyone here. When picking words, some of us might make a suboptimal choice. Ask yourself whether you would have had the same reaction if Vektorceraptor had picked "uprooted" instead of "rootless".
Thomas was asserting that "rootless cosmopolitan" was an antisemitic slur that Vektorceraptor deliberately applied to Kenarov. I asserted that the knowledge and usage of that expression is not nearly as universal as Thomas claimed. Thomas clarified that it's a Russian dog whistle.
I've just finished reading the essay you linked there. How does it fit in this discussion?
Edit: Also, I don't really know whether Kenarov is in any way Jewish but it's not hard for me to imagine someone using the term satirically but not intending to (at least, not strongly) evoke its antisemitic aspect. I don't think that really works in English and aimed at a Western audience but people do irony-recycle the old slogan tropes quite a bit and it's a linguistic theme throughout the piece.
The ideological terms where picked fairly carefully with an eye towards 'ideological soundness' and had multiple purposes. 'Rootless cosmopolitan' was an antisemitic dogwhistle, it was also part of a deliberate effort to shift to a more Russia-centric Soviet ideology. In a way it was also a Russian dogwhistle so tptacek was kind of right after all, completing the pedanticircle.
I regret (and did even at the time) using the words "dancing around" --- I was just waking up (let's not discuss the unhealthiness of "commenting on HN" being one of the first things I did after regaining consciousness) and even as I wrote it was thinking "this conveys more intentionality than I mean to".
So for that bit, I apologize! People still should aggressively avoid the term. I only saw this thread because I've been on a sort of comment bigotry scavenger hunt with "rootless cosmopolitan" as one of the items.
I wouldn't casually use it in English, though, precisely for the reasons you outline.
It was also quite informative to learn about this phrase and its nuances.
I'm still trying to figure out what you're trying to say, though.
If your point is that there was plenty of bigotry in old Yugoslavia, then yeah, I know that. It's still alive and well in the remnants of it. The casual bigotry and rampant nationalism are part of the reason why I'm still "rootless", because I wouldn't fit in with my compatriots anymore.
But none of that was really the point here. The point is that a phrase might be very well recognized by some people here and totally unknown to others who might stumble into using it by accident.
I mean, I don't actually know if Vektorceraptor was being deliberately antisemitic or not. Maybe Vektorceraptor did know it and its antisemitic connotations and used it like that on purpose. Or maybe not, maybe it meant what I read from it and described in my reply.
Yeah, it's fascinating to read the history of that expression, and to find out it's not a "Western", but a Soviet expression. But I'd like to offer a gentle reminder that the countries that comprised the Soviet Union are one set, and the countries that used to be in the Soviet sphere of influence is another set, and they're not the same set.
The simpler, calmer point to make is: just don't non-ironically use the term "rootless cosmopolitan" on HN.