That's not actually what they describe. They describe catting known_hosts and seeing terminal.shop with the given key in the output. That won't work if you don't continue to connect because known_hosts won't be updated with their key. Additionally, if hosts are hashed, you won't see terminal.shop anyway.
I think what "cat" here means is that you are supposed to add their key to the known hosts file manually before you connect. Showing the output of "cat file" is a way of saying "this should be in the file".
I think it’s fair if they want to assume a certain competence from their audience, and they’re being cute. But these aren’t instructions and if they are, well, the ssh command happens first.
