I'd love to see how that text message !privacy ruling conflicts with !copyright law. Copyright is owned by the author of an original work, and without explicit permission to copy that work it could be argued it's a violation of copyright to distribute an original work in a text message to others, including the police.
The Silence app is needed on both sides for encrypted texting. If the sender doesn't have the key for the recipient then a key exchange message is sent automatically, followed by the encrypted message. If the recipient doesn't have the Silence app then the message is sent in plaintext. I don't know the details of the key exchange, or what overhead the key probing incurs. !crypto