I just finished a long process of rebuilding a Windows system "from scratch" because a user installed a version of Audacity that had been corrupted with all sorts of virii, malware, adware, browser redirects, and I'm pretty certain a keylogger too.
The problem isn't the Audacity project itself. The problem is that it's becoming easy for shady organizations to fool users into installing their subverted version.
Trademarks do present some minor risks to software freedoms (making it harder to use freedoms), but they also provide real benefits without actually preventing users and developers from using their freedoms. So while I understand Debian's stance, I think there are some very good reasons to have and use trademarks for FLOSS projects.