Does GNU GPL incompatibility mean not 'open'?

News and commentary that the new Office XML formats are not compatible with the GNU General Public License - and therefore not 'open' - prompts Microsoft's Dare Obasanjo to respond:

"There are two points I'd like to make here. The first is that "being GPL compatible" isn't a definition of 'open' that I've ever heard anyone make. It isn't even the definition of Open Source or Free Software (as in speech). Heck, even the GNU website has a long list of Open Source licenses that are incompatible with the GPL . You'll notice that this list includes the original BSD license, the Apache license, the Zope license, and the Mozilla public license. I doubt that EWeek will be writing articles about how Apache and Mozilla are not 'open' because they aren't GPL compatible."