Fair enough, it is mentioned. But in the episode (I'm watching it now) they've taken the limo of a right-wing asshole author and the document he's reading is supposedly the real limo-owners speech he's going to give. They literally call him a "right wing Ayrian Neo-nazi" in the episode. So they're trying to associate those ideas with calling people nazis. And they reiterated the Nazi name many many times throughout the episode. A guy who is "head of the Ayrian unions" and "responsible for bringing hate-mongering and fascism back in to fashion".

Larry David talked about some real edgy stuff from time to time, that's why the show was so popular. They didn't actually discuss it at all, they just said it. I don't think this constitutes a "code", just an awareness of the world around him. But presented in a propaganda light, as if anyone who believes in the existence of ZOG is immediately a Nazi.

But the way it's slipped in so nonchalantly is interesting, and it's probably the only way such a phrase would make it on mainstream American television. But they're clearly implying that if you believe this, you're a deranged right-wing Nazi. That's propaganda, not a release of information...

So in reality what we see is a super-typical propaganda narrative, in the form of a limited hangout. Not a "code" but instead disinformation that plays off reality to be extremely effective.