Hi Sam, I think you have muddled up WS with Niger.
WS reported closed south of Tan-Tan (for foreigners) but I am sure will re-open soon. It was only a riot which happens there once in a while and only became news because many people were killed.
The actual war ended years ago and most tourists transit without ever seeing a Saharawi camp.
Alg-Niger crossing (main central Sahara route) is more complicated and will stay that way. Was 'reported closed' after latest kidnappings, but this is Niger. A guy came through a week or 3 ago and chose to have an agency escort from Assamaka to Arlit (200km piste) for his protection @ €150/day (see the link - the story is not complete).
Earlier this year when north Niger was actually worse with bandits (separate issue from AQIM kidnappers, IMO), the army were trying to charge €500 to escort 200km to Arlit (ie: extortion).
Escorts/guides were only ever required in Niger for Aïr and Tenere, regions east of the trans-Sahara Highway, but tourism collapsed there 2 years ago for various reasons (and probably explains the banditry).
The daily military escort down the road from Arlit to Adagez continues and is free AFAIK, though as often is the case, has dubious actual value if you dont keep up.
I don't think agencies will want the work from Assamaka to Arlit as it is not simple tourism like the Tenere. They'll get robbed like anyone else. Even in Arlit they will advise you to misinform people about your itinerary and timings to avoid a set up (if heading north that is).
Escort is a job for the army in technicals, and if it is necessary (as on Agadez highway) it should be free, just as Dakhla to Mori border used to be, or east Iran and Pakistan are today.