That's steganography not cryptography and generally considered to be the red-headed bastard step child of actual intelligence work. Don't be ridiculous.
Its some 4chan racist idiot's idea of a red herring.
Making sure a message doesn't contain identifying words/phrases/idioms/slang and making sure it cannot identify you through statistical analysis are not steganography and both are things I would expect any security expert (you know, like the people working for the NSA) to do if they want any hope of remaining anonymous.
Without any science behind it or having first hand access to the source for the tools used to identify such words/phrases/idioms you're just amateurishly putting lipstick on a pig.
With how much caution they are taking against a nation-state adversary, I think it a bit short-sighted to think that this is just "a racist idiot's idea of a joke".
There is a large body of science behind author identification, with lots of academic papers, talks at hacker conventions, etc. I'm surprised you missed it. If the NSA did use authorship identification software, would it be unreasonable to believe that a privileged leaker would have access to such a tool? I believe that it is more likely than not a joke, but it has the same effect as a right handed person signing their name with their left hand... unless they have a habit of making "In Soviet Russia..." jokes - then they're screwed.
They probably spent a lot of time on the message. Coded words or phrases. Embedded keys. Resistance to identification analysis.