The suggestion is nice though since an attacker would have to break both at once. If you conceal an SSH server, you'd first break the obscurity, then proceed with attacking the SSH server. The suggestion seems to be that you would have to break the cryptographic part to reveal the server (which is then supposedly secured by "normal" cryptographic means, such as a regular SSH server). That is, you are dealing with cryptography just to be sure the server exists at all.
I'm all for defense in depth but I don't see the point of a redundant cryptographic layer. It's not trivial that it doesn't broaden the attack surface instead of narrowing it.
If the argument is that a steganographic layer that involves cryptography does a better job at concealing than a similar layer that doesn't I'm also not convinced. Cryptography helps against MITM scenarios, but at that point the existence of the service is already revealed.
