The "global south" is a term which originates in writings about the vietnam war in the 60s. It's by no means a new term.
Use third world country if you want, but at least in my mind, the terms "first/second/third world" are more tied to which hegemony you fall under, where the first world is the US hegemony, and the third world is without a hegemon. "First world" is kinda synonymous with "the west". To me, the term "global south" communicates that it's being contrasted against all of "the north", both east and west, while using the term "third world" communicates that the context makes a distinction between "the west" ("first world") and the old eastern bloc ("second world") somehow relevant. Some "second world" countries such as China are also part of the "global south".
I'm sure there are people who use the term "global south" simply because they perceive it to be less judgemental somehow, but I might've used it in this context because "third world" communicates something different.
Honestly though, I would've probably just used the term "non-western" (maybe "non-first-world"?), since that's the distinction the article actually draws. Eastern Europe is also affected here, after all. Or maybe I would've drawn the distinction at "US" and "non-US", since Europeans don't necessarily want their writing to sound American either and the old US hegemony seems to be on its last legs.
Use third world country if you want, but at least in my mind, the terms "first/second/third world" are more tied to which hegemony you fall under, where the first world is the US hegemony, and the third world is without a hegemon. "First world" is kinda synonymous with "the west". To me, the term "global south" communicates that it's being contrasted against all of "the north", both east and west, while using the term "third world" communicates that the context makes a distinction between "the west" ("first world") and the old eastern bloc ("second world") somehow relevant. Some "second world" countries such as China are also part of the "global south".
I'm sure there are people who use the term "global south" simply because they perceive it to be less judgemental somehow, but I might've used it in this context because "third world" communicates something different.
Honestly though, I would've probably just used the term "non-western" (maybe "non-first-world"?), since that's the distinction the article actually draws. Eastern Europe is also affected here, after all. Or maybe I would've drawn the distinction at "US" and "non-US", since Europeans don't necessarily want their writing to sound American either and the old US hegemony seems to be on its last legs.