Sure, it looks easy to memorize. There's one thing I'm probably misunderstanding:

it seems to me that the connection has no identification, authentization or authorization whatsoever (as these are the parts that Mosh offloaded to SSH, by design): if you know the port, you're in.

What am I missing?

Edit: ok, I see, you need to also input the MOSH_MALLET_HMAC_KEY and MOSH_MALLET_CCRYPT_KEY into the client. That...helps. Are they static, though?