Zacchiroli explains the reason Debian is not listed in the FSF approved list, "Historically, one of the main argument to exclude Debian from the free-distro list (argument we have share with essentially all other popular distros) has been non-free firmware in main. This argument has become moot since the early days of Squeeze development (early 2010)."
Zacchiroli has been in touch with FSF director John Sullivan to discuss the reasons of Debian absence from free-distros. Based on that discussion Zacchiroli plans to setup a team of people who assist in either getting Debian in FSF approved distro list or document the reason why they are not there.
He has created a mailing list where interested volunteers can work towards achieving this goal.
Zacchiroli says, “I'm looking for Debian volunteers interested in the topic and willing to participate in a joint Debian / FSF team that will work toward that goal without prejudices. The ideal outcome is an agreed upon list of Debian "bugs" that need to be solved, according to the usual Debian mechanisms, and with no special treatment due to their "political" origin. The public [fsf-collab-discuss] mailing list has been setup for the activities of such a team. If interested, please join the list and say "Hi" there."
According to FSF, the biggest issue of not including Debian is lack of separation between Debian's main repos, contrib and non-free repos. If these issues get resolved, we may soon see Debian along with Blag Linux, Dragora, Dynebolic, gNewSense, Musix, Trisquel and other FSF's recommended free software distros.