Yeah, that's not it lol
Post modernism is a philosophical, artistic and scientific movement of the 20th that pointed out big flaws of modenism and universalism. In Art it CAN be a reject of the structural nature of modernist medias (which is usually why people could say that Modern reactionnary are post-modernist) but that's just a fake appearance.
In reality, post-modernism forces us to adopt an outward vision of the world, a vision that is not absolute, not centralized on big stories or absolute concept such as nationalism or gender, but more scattered narratives and identities. it's more than anything a way to push the voices of the marginalization. This is why post-modernism was very usefull for social struggles all over the world.
In reality, the concepts of "objective reality", "absolute truth", "dogmas", "rationnality" and what you describe as "personal truth regardless of empirical facts" are more linked together than you think. The "personnal truth" of Ravager (but also the one of many people here such as Zenos for ex) are ALL linked to this twisted vision of rationnality resulting from the beliefs of the age of enlightement..
When Ravager is saying "BIoLoGyyyy!!" what he is actually saying is "I believe in the basic notions of science that were taught to me as a child" and what he doesn't know is that those notions are - for the most part - the result of capitalist, imperialist, colonist system and the early stage of rationnalism +universalism themselves. All reactionnaries here are stuck in a world between their basic knowledge of the world (modernism+ universalism + the cult Rationnalism) AND a big rejects of anything that tries to counter the inherent biases of the modern age, capitalism, imperialism and colonialism (and other systems)
As such, they will claim to know everything about science while rejecting ALL the work that sciences managed to create after its self-critic that arrived with the help of marxism, historical materialism, postcolonialism, post-modernism, structuralist and post-structuralists.
So no, Trump or Ravagers are not post-modernists, they are the complete opposite.