That's a newspaper article without a by-line. (Or if there is one, I missed it.) Presumably, if there's a ritual reference there, a brother either wrote the article or at least provided background info to the writer.
In my experience, this kind of reference to ritual is not unusual. Our early leaders did it, though granted in writings intended mainly for brothers. I imagine other groups do it too. The key is that, like with the article you posted, no one outside the fraternity would have a clue what is being referenced—unless, that is, someone calls attention to it (like you have just done.
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Sigs can be a different thing, which is why I prefer that brothers stick to traditional closings in letters. That said, I haven't encountered signatures that give anything away. I have, a few times, encountered strings of letters about which I and others had to ask "what in the world does that stand for?"