This implication is purely in your head. The article and the scientist whose work it describes are just pointing out the identification of some data that's been transmitted across a public channel for years without anyne noticing.

> Since it's broadcasting all the time, there's no need for steganography or covert transmission.

Well, you could look at it that way, or you could say that the fact that it's broadcasting all the time is the steganography. That constant transmission of nonsense that nobody wants is what makes it fail to be suspicious when you send a message that somebody does want.

Its all comes down to what we buy as the definition for a number station. For me a number station needs sends a message to be a number station, not a key.