My usage is a well-established if secondary meaning. See for yourself: http://www.merriam-webster.com/dictionary/shibboleth, http://dictionary.reference.com/browse/shibboleth, http://www.google.com/search?q=site:wikiquote.org+shibboleth, even (selected at random from project gutenberg texts) http://www.gutenberg.org/files/356/356-h/356-h.htm. Can you find a better word? I'd happily replace it, but I can't think of any other that means a platitude that happens to be false.

Just to get back on topic, I'm disappointed that no one else seems to appreciate the beauty of oscargodson's question. It's one of those things that is dope-slap obvious, but only once you see it.