Well to be fair, all there is to go on at this point is that document. The blog is pitched at a wide audience and is meant to be a "light" entertaining read, rather than something in depth and technical. But agreed, it would be interesting to know the exact process of "extracting" the coded message. The point of the article is that it was there (or to your point, it was claimed in court that it was there!), rather than how it got there. Bottom line - it did the trick.