You're exactly right and I think it's important to consider that the LA Times' position as a sort of authority figure when it comes to speech (being a major news source/ media entity) may be an underlying interest in how the arguments made in this article are put forward. I imagine a whole lot of editors of the last few newspapers that are independently owned had some very interesting thoughts when the workers at New York Times pushed out some of it's leadership over an article Tom Cotton could have just as easily put on his website.

I agree that it's about cultural norms but I think the cultural norms are the cost and limiting factors of free expression being greatly reduced. I imagine an entity like the LA Times has an interest in defining how free speech works in the news room and subsequently the readers of that news source. I also imagine that idea of free speech would protect leadership in the newsroom from subordinates if everything published has to go through said leadership.