The fact that this article got published says more about Trump's appeal than the content of the article does.
As others have noted, the article's argument is weak. The author found an oddly unqualified source (a PhD candidate at Penn????) to give some quotes about lack of diversity in the media, and then tried to tie in that lack of diversity to Trump's appeal. One tiny data point in the article (that only 7% of the media are Republican) is relevant. The rest is worse than extraneous. It's utter nonsense that makes clear the author has no idea what she's talking about. To suggest that Trump supporters are at all angry that white men, rather than minorities and women, are dominant in the media is the height of absurdity.
To put it bluntly, Trump supporters don't care about that shit.
What they do care about is lack of opportunity for themselves and their families, and it's no accident that they're mostly working class whites. To demonstrate how working class whites get screwed in our current hierarchy of wealth and privilege, look no farther than this article.
The author, Valeria Pelet, is a recent graduate of Harvard, who landed a high prestige job at The Atlantic. Was she qualified for this job? Judging by the quality of this piece, no. Was she qualified to go to Harvard? Judging by the quality of the writing she displays here, and the lack of coherent thought or ability to make a persuasive argument, again, no.
So how did it come to pass that she got into Harvard and landed a job at a prestigious media institution? A quick Google search combined with this article tells us that:
1) She was born in Puerto Rico.
2) She is willing to play her Hispanic immigrant identity card for all it's worth (she studied Latin American history and wrote her thesis on 'the political evolution of a Puerta Rican urban music band' - source here https://valeriampelet.wordpres
3) She is willing to carry the water for the cultural hegemony - witness how hard she tried to tie in the narrative of a racist America that is dominated by white people into an article where that line of argument isn't just out of context, but entirely out of place.
In other words, Ms. Pelet herself is evidence of why Trump has become so popular with working class whites. Ms. Pelet clearly doesn't have the intellectual acumen to be among the elite of the elite, yet she got into Harvard anyway because, if you're Puerto Rican, you don't need to be elite. You just need to be good enough.
The child of a working class white Trump supporter, who gets higher test scores than Ms. Pelet, who writes better arguments than Ms. Pelet, and is capable of doing better work in journalism or any other rigorous field than Ms. Pelet, doesn't get into Harvard. The child of a working class white family barely gets into State College, and does so with no scholarship money, even though she had better test scores than most of the minorities who got financial help.
The child of a working class white family doesn't get a job at The Atlantic, even though she can write a better column than Ms. Pelet just did. Worst of all, even if that child did get a job at The Atlantic, she wouldn't be allowed to speak the truth as I am doing in this comment. She'd have to create spectacular logical leaps that both condemn Trump supporters as dumb racists while also condemning the media for being dominated by the white male patriarchy. She'd have to write nonsense, like Ms. Pelet just did.
Ms. Pelet has shown herself worthy of that kind of work, which is why she got the job, and is also why working class whites are pissed. People are lining up behind Trump because, whatever his flaws, he's not buying into the bullshit system that got Ms. Pelet a job at The Atlantic, but instead, is promising to overthrow it.