I don't think that we implied that by testing with a fake virus that you will be protected from every new virus. Perhaps we could have explained it a little more clearly, but after re-reading the article, I think we correctly told everybody that it isn't a real virus.
When we say "testing" your anti-virus, we meant testing whether it is installed and configured correctly. For instance, from the article:
For example, if you’re running antivirus software on a Linux mail
server and you want to test that it’s working properly, you can email
the EICAR file through the mail server and ensure it’s caught and
That said, I understand your point of view, and I'll add a quick note to the article.