One can understand how concern would arise over the potential for random use and misuse of the Debian mark!
To borrow an analogy given elsewhere, if I owned a Mercedes-Benz auto dealership, then, with Mercedes-Benz' permission, I might call the dealership Thaddeus Black Mercedes-Benz. Such a use of that mark would be descriptive in nature. On the other hand, Mercedes-Benz would not wish to let just any random person use the mark without restriction, would they? To permit this would defeat the mark's very purpose. Their dealers are formally certified, and, presumably, bound not to misuse the Mercedes-Benz mark to describe, say, a dealership that mainly sold Buicks. Perhaps Debian's use of the descriptive word GNU, as in Debian GNU/Linux, might be viewed in a similar way. This usage is naturally not meant to imply that Debian is GNU; it is given merely as a proper descriptive term. If Debian wished to arrange a formal certification program, governing the proper descriptive use of the Debian mark at Debian's discretion, where would we go to apply, please, for Debian mark certification?