At least from my interactions with this line of argument, this stems in part from an appropriation of postcolonial thought - taking the very straightforward critique that Western powers present themselves as bastions of tolerance and inclusiveness in contrast to the Global South (a place uniformly positioned as "without democracy," uncivilized, and backwards) in order to advance Western imperial aims, terfs and other anti-trans reactionaries use this critique as cover to smuggle in deeply racist, deeply Western notions about gender, ultimately reproducing Western hegemonic knowledge structures through this supposedly postcolonial criticism; this is part of what underlies the argument that terfs are racist (in combination with all of their explicit racism + coalition building with fascists).
Jenny Andrine Madsen Evang has a fantastic paper on this topic from 2022 titled Is “Gender Ideology” Western Colonialism? Anti-gender Rhetoric and the Misappropriation of Postcolonial Language* which works through much of this argument, which I will highlight select portions of, although I recommend people read the full thing:
First, transgenderism is positioned as a Western imposition on the vulnerable masses of the Third World. The West in this instance is framed as exporting its own cultural decadence - the original source of "gender ideology" - and forcing it onto the innocent victims of the Global South, who are framed as universally more traditional in terms of gender, sexuality, and family structure. Here is the first instance of cultural essentialism that is endemic to Western thought, just with the moral language inverted - the West is the source of decay and destruction in this case, while every society, culture, history, and people outside of the Western core is uniformly more "traditional" (primitive, closer to nature) and therefore more pure and stable, incapable of keeping pace with the rapid social and cultural development of the West. anti-trans activists championing this line of reasoning then take the usual white saviour position of needing to save the Global South from the West's destruction of their culture - as Evang puts it: "white women are saving brown women from decadent western 'gender ideologues'" (p 368).
This argument takes on a particularly racist and insidious form in the panic surrounding (white) transgender children, who are "represented as emblematic of a new, socially engineered human, devoid of history, and external to the pillars of Western biology, politics, and culture." (p 372). The fears of the rootless, history-less trans child being led astray from 'proper heterosexuality' is bound up in white extinction fears (p 377). Evang highlights the problem with turning this into a simple rhetorical gotcha, where people (rightfully) point out the contradiction between the claim that, on the one hand, gender is supposedly innate, natural, and (in some cases) ordained by God, but on the other hand, is a property of the body vulnerable to corruption, propaganda, and social manipulation. Rather than merely dismissing these people as stupid bigots, this contradiction highlights the white supremacist assumptions that underlie these two seemingly contradictory positions: that sex is a civilizational resource in need of constant European cultivation and refinement, akin to white colonial dominion over nature and its material resources. As Evang says:
Sexual dimorphism and proper gender roles — the highest treasures of the anti-gender movement — historically functioned to illustrate the capacity of whiteness for progress, evolution, and national/personal self-discipline over and against the un/gendered, racialized person. (p 378)
Evang is partly drawing from the work of decolonial feminist Maria Lugones, who makes the argument that gender is a colonial technology of power that grew alongside the global system of white supremacy and is therefore inherently racialized, as colonized populations are positioned as the labour pools, property, and resources of European powers - effectively, they are positioned in the Western imaginary as animals, which have no gender, only a sex (you can read one of her papers on the topic here).**
I bring all of this up because in order to frame transphobia/transmisogyny (an affliction only suffered by Western degenerates practicing 'gender ideology') as a "white people thing," you need to accept a progressively more and more racist chain of arguments about "authentic sex" being under attack. Again quoting Evang:
Thus, non-Western cultures are seen as resistant to “gender ideology” not because of their advanced grasp of the cultivation of “authentic sex” but because of their “coarse and rigid” prehistorical ways and nonplastic biology. This leads us back to the internal differentiation of “gender ideology” victims as either leaders or followers: while the anti-gender movement, particularly its iteration in parts of Eastern Europe, is framed as resistant to “gender ideology” because of its well-developed capacities for reason, sentimentality, and proper gender roles, the non-Western world is framed as resistant because of its lack of capacity to evolve, its biologically entrenched psychic structure wanting in refinement, impressionability, and sophistication.
Underlying the white child’s sex is centuries of accumulative civilization that imbues it with advanced impressionability — this is what allows it to be represented as at once the beacon of the West’s future and the ultimate victim of gender ideology. This overdetermined anxiety is well exemplified by the TERF discourse vilifying the misguided trans* child and teenager through the specter of the so-called epidemic of “rapid onset gender dysphoria.” (p 379, emphasis mine).
In order to argue that transphobia is a laughable, self-inflicted symptom of Western decadence exclusively practiced by white people, you need to argue that:
there is a universal notion of a non-white, non-western gender system, one that is inherently more traditional and closer to their natural, animalistic sex, which is unchanging across time and space,
even when non-western people practice "gender ideology" they do so only in a primitive, exotic, distorted reflection of original Western gender, incapable of their own "real" relationship to gender, and
transgenderism is a social contagion that is leading us towards the edge of societal catastrophe, where the European capacity for reason will be destroyed as we can no longer "even define what a woman is."
*link is open access. If it doesn't work, you can go to google scholar, paste the title into the search bar and click on the duke university press link that appears beside the article.
**for a specifically transgender and intersex extrapolation of Lugones' work, see also Adamson (2022)