Allowing people to do things you disagree with is the whole point of free software, not just a minor quibble. See also Mark Pilgrim's great essay: Thank you for giving me the opportunity to explain this to you.
(When it comes to freedom, I side with Debian over the open source people or the GNU nuts. I think something like the third clause of the BSD license combined with a trademark for the book title (if he cared enough) would've been enough to address the issue invariant texts were meant to address in the non-free GFDL.)