Have a long and frustrating wank to Cosmopolitan because I'm a teenager and haven't figured out I can just walk into a newsagent and buy a copy of Penthouse.
Because analysing network traffic wouldn't allow an adversary to see what you're sending with Signal, but they could still tell you're sendig a secure message.
What the Guardian is doing is hiding that secure chat traffic inside the Guardian app, so packet sniffing would only show you're accessing news.