I am not a Mac user, anymore.
Generally, Word does not see things in text boxes to the same extent it does things that are in the regular document layer. In Word 2003 and 2007 text in text boxes does not show up in the Word count in document properties.
Here is a screenshot from Word 2010 showing both the status bar word count and the document properties word count. The difference is the text in the text box.
My understanding is that Word 2011 is a cross of features between Word 2003 and 2010.
This is the way Word is built. MS may get around to rationalizing it at some point, but I would not advise holding your breath.