I believe I gave a perfectly legitimate reason in my original reply.
There is an ongoing dispute, as mentioned by ADFENO, about whether non-functional data under non-free licenses create any ethical problems or not. Stallman and the FSF seem to think they don't. Debian project seems to think they do.
Even as a longtime advocate of copyleft CC licenses, I personally agree with RMS that the Debian project policy against even asserting a trademark, so users can clearly distinguish between one group's version of a software and another group's, is an under-thought knee-jerk reaction against any form of "intellectual property". In other words, they have fallen into the exact trap of mixing up patents, copyrights, and trademarks that Stallman warns against [1], instead of evaluating each of these legal traditions on its own merits.
[1] https://www.gnu.org/philosophy/not-ipr.html
