Actually, no. It's because of Mozilla's terms of licensing that trademark; for example, demanding the right to code review for anything published under that trademark. Mozilla's demands are sensible, but they apparently don't work with the rules that the Debian uses.
but since it is open source they can make a free copy and put their name on it instead
And they can't do that with your beloved BSD license?
Again, I don't "love" any open source license, I've simply recommended the ones for you to use that weren't so clearly tied to Stallman. But you've always preferred Stallman's version of "free", even though it really isn't and has that nasty little catch in there where you have to give your own work away for free if you ever try to sell it for a profit.