I remember seeing in a documentary that decoding an unknown signal to make sense of any meaning it possesses requires that some parts of the message be repeated on a regular basis. As our own communications have become more efficient, however, there's less and less room for repeated 'characters'. This has led to the realization that if our own modern transmissions were received from deep space in the guise of alien communications, and we didn't have the key to decompress and decode them, we in fact wouldn't be able to decode them, and they would be discarded as nothing more than noise.
I think the documentary was dealing with the question of 'what if we stumbled on an alien transmission from one point in the cosmos to another point in the cosmos'. Here, we might be dealing with a message which is intended for a more advanced civilization, where we just crossed the beam by accident. In that case, it would make sense that we wouldn't be able to discover the meaning of the message.
The article you referenced would better apply to a lighthouse-type signal, or maybe a signal targeted specifically at Sol with a Rosetta Stone encoded in it, a la Carl Sagan's 'Contact'.
Of course, all of this is tempered by the huge amounts of time it takes for messages, and the photons they travel on, to move through the galaxy.