If the data is going through the air or a wire it can be sniffed, right? Is every message signed or encrypted like ssl/tls, or is this just some kind of extra header(s)?
And then, even if you could look inside, there's another type of asymmetric cryptography going on: the remote attestation itself. Again, if properly designed and possibly backed by a hardware security chip, it cannot be spoofed. This isn't something trivial like a shared secret in an HTTP header.