Speaking as an ex-journalist, who never wrote for gaming magazines or websites (never wrote professionally about games at all) I have a couple of things to say about gaming journalism. First of all, there's no such thing. Don't take that as a criticism, because it's a fact. There's a lot of ethical matters that other kind of publications have to abide to, that aren't true in gaming journalism (and also other niche publications as well, but it's about gaming I'm writing about now).
As an example, a news article never, but never, should contain the opinion of the journalist. It does happen in the mainstream media, but it shouldn't (Fox News or british tabloids aren't role models). It happens a lot in gaming journalism. It happens so frequently that I could say it almost always happens to a certain degree. I suppose that gaming journalists know that they are addressing a crowd who doesn't care about the ethical side of a profession, and look at gaming news with a lighter disposition compared to what they would if they were political or economical news (and that's just fine). Also, I'm pretty sure that most gaming journalists never had experience in other fields of journalism. Some, probably, aren't really journalists, they are gaming experts (and that's also fine, readers care more about their knowledge of games than their grasp of media tecniques and styles). Also, gaming opinion-makers are also journalist, and that's a big faux-pas in other kinds of journalism. There are other matters that I could address, but this is enough.
So, what about people (usually politics, celebrities, soccer stars and millionaires) or companies black listing newspapers or TV stations? Is it right? Is it common? Well, if it's right or not, it's anyones opinion, but it's a right they have. No one has to explain why they don't give interviews to a certain newspaper. People just say no, and if you insist they will hang up on you. You can still write/ talk about them… Some newspapers or TV stations just give them back the cold shoulder (and in the case of celebrities or companies there's a cost to that partial lack of media coverage), others enact their reveng whining about the silence (the way Kotaku did), or even trying to uncover nasty things about the person/ company at stake. So, the rightness of it is a matter of discussion, but it happens. It happens a lot, and mainstream media it's unusual to cry about that (there are, of course, ridiculous episodes that I will not discuss here because they hapenned in my country, and nobody cares about Portuguese affairs).
So Kotaku is whining about Bethesda and Ubisoft. It's their right. But it is ridiculous and if gaming journalism was as fierce as mainstream media they would be the butt of the joke by now.