It looks like every message in this system create a new Bitcoin Cash transaction. Is that a good idea? You don't really need the consistency guarantees of the blockchain, so any gossip protocol would work equally well, and you wouldn't need to keep every message around forever.
Also, this leaks unnecessary metadata. If you know Alice's address, and you know that she talked to Bob at 8:05 yesterday, you can figure out Bob's address by following the money.
Also, this leaks unnecessary metadata. If you know Alice's address, and you know that she talked to Bob at 8:05 yesterday, you can figure out Bob's address by following the money.