Of course it raises the question of what constitutes forbidden speech. To answer that I would look towards the opinions you are already frightened to voice publicly.
https://www.popehat.com/2012/09/19/three-generations-of-a-ha...
(brief excerpt from a much longer piece: "Holmes' famous quote comes in the context of a series of early 1919 Supreme Court decisions in which he endorsed government censorship of wartime dissent — dissent that is now clearly protected by subsequent First Amendment authority. The three cases in question arose from socialist criticism of conscription during World War One. The criticism at issue, to modern tastes, was a clearly protected and rather mild expression of opinion.")
Don't be silly! I understand the interpretation of information in a conversation; if someone were doing this I could tell. But I don't understand cryptography mathematical mumbo-jumbo. Therefore these two situations are nothing alike. Let's ban crypto.
I agree that steganography can be a solution to sustain open communication. It's less brittle than crypto but offers weaker guarantees. I know of a suitable system design. Not plain English, rather plain bitfield.