The Thermian Argument was coined by joyless social justicey types to criticise 'problematic' content in fiction, by those arguing (often disingenuously) at cross-purposes about the lore, because fiction, by it's very nature is not real.
So, you can't argue that Princess Quimavere from the mystical kingdom of Cameltoe goes into battle in a chainmail bikini, because it's her choice as an independent woman in her culture where her people all just happen to choose to dress that way, because she isn't real. She was created by an artist who deliberately made artistic decisions in her creation, usually to illustrate a message that that creator wanted to portray.
Unfortunately for them, however, the Thermian Argument can also be used quite effectively to criticise all the shoehorned in DEI progressive tokenistic shit that they like so much in media nowadays. That character can't just be a black woman, someone on the creative team decided that that character should be a black woman, and there was probably a reason they were influenced into that creative decision.
Honestly, I kind of hate that this has rankled me so much that I've written a whole spiel about it, because it's so fucking inconsequential (although, I do wonder, if people are going to argue that it's inconsequential, why couldn't that character have been - gasp! - a white man?) but fuck it, it really stuck out to me and I feel like I notice stuff like this more and more nowadays.