Yeah that's a good page and covers the weirdness of the term well. You read 'rootless cosmopolitan' in English and think 'ah yes, Soviet antisemitism and Stalin's abortive final purge'. And that's not at all wrong! But the term as used by the Soviets is not a simple euphemism like, dunno, 'urban youth' is in the US.
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.