I don't know much about Yarvin but I imagine his point is the universities indoctrinate the teachers and the journalists who in turn indoctrinate the public.
If universities are really brainwashing people, then those who own the media can just not hire those brainwashed people. Power over hiring is the ultimate level of control over any organization, media companies included.
You can make the argument that the media needs an audience, and if the masses are brainwashed then they have to speak in that language. But if you're talking about non-objective-truths such as values, and those values are so widespread that media has to cater to them - that's not brainwashing, that's just popular culture.