Hi thomasmilo!
Yes, Sabnzbd would not be allowed in the Trisquel repositories as it requires
the non-free unrar. Fortunately, this is easy to overcome. If you install
python-cheetah, unar and par2 from the Trisquel repositories then you can run
Sabnzbd from the python source files available from their main site. You just
need to make sure that the file Sabnzbd.py is execuatble (right-click, and
check the appropriate box).
Ignore the message saying that your version of unrar is not recommended. The
par2 check function of Sabnzbd will still work and you can unpack your files
using unarchiver - open a terminal and cd to the folder containing your
archive files and unrar them with: unar [filename][extension]
