If you're serious about security, scp is not secure (open to man-in-the-middle attacks) until you've transferred keys via some other channel or use a PKI that you actually pay attention to.
But that is being ultra-paranoid in my book.
Hopefully Linode doesn't have any internal gremlins.
Of course, the weak point there is SSL where the keys themselves are transmitted, but it did well to quell my paranoia.
2. If you are setting up servers, you may want to transfer the server public (not private) key to client, but what's the point? Ssh/scp will do it for you anyway, and you already know the remote end public key fingerprint anyway -- since you are setting it up.
So, no, "ultra-paranoid" doesn't explain the pastes in question. "Ultra-ignorant" does :)