Unfortunately, the term "open source" itself is subject to misuse, and because it's descriptive, it can't be protected as a trademark (which would have been our first choice)
this is just like the gnu/gpl shit*. they try to take a commonly used word or phrase and define their own meaning for it - they then try to stop anyone using that word/phrase for the whole host of different things it already means.
they have no authority except a crappy logo yet they expect to be taken seriously.
*free/Free/freedom/etc