I found a nonfree package

It's important not to mix up the DFSG, standing for the Debian Free Software Guidelines, with the FSDG, which represents the GNU Free System Distribution Guidelines. The difference might seem minor, just a matter of rearranging a few letters, but the implications are significant. According to the documentation for a certain package, Debian chooses not to include it due to its adherence to the DFSG. Meanwhile, the GNU guidelines have distinct requirements, and what constitutes a breach of one set of guidelines doesn't automatically imply a breach of the other.

In the case of Trisquel, it's permissible to include this item. The issue for Debian revolves around the inclusion of Front Cover Text and Back Cover Text under the GFDL. This license mandates that all versions of the documentation prominently display "A GNU Manual" on the front and "You are free to copy and modify this GNU Manual. Buying copies from GNU Press supports the FSF in developing GNU and promoting software freedom" on the back. It appears Debian finds these stipulations to be too much. :)