It's some kind of fuck-up, that's for sure, but unlikely to be of the kind that's being intimated by the press. It's not like they've landed and been overpowered then nicked, imo. If that had happened to an SAS unit you'd expect lots of dead farmers, some dead troopers, and no eggs for breakfast.
What's far more likely is a breakdown in communication at another level. If they wanted to make contact with any rebels they'd have walked off a ship in Benghazi. More likely they were supposed to make contact with person or persons specific (e.g. an SAS unit accompanied by a government representative could be an operation to extract a defector or prisoner).
Perhaps they did that and got captured afterwards by people unaware of the mission, then got released when they were clued up; or they ran into these "farmers" who prevented them from completing the job but seemed to have made them pretty welcome all the same. Maybe the "farmers" even arranged for the completion of the mission (hooked-up the team with who they wanted to meet whilst they had a kip and some eggs). The former and latter could explain the mission being reported as a "success" I suppose.
Whatever happened, something has prevented the unit from engaging the "farmers" and my bet is that is diplomacy rather than them having been overwhelmed. The SAS (if indeed that's what they were) have chosen not to engage, probably because the other chaps were seen as friendly. I doubt it was because they had rifles up their noses.
So I'm going for an intelligence fuck-up rather than and operational one. Can't see what else would explain a seemingly zero body count, fluffy incarceration with nice breakfast, and lightning fast release, presumably with all their equipment, and possibly with one or two "guests" that weren't with them when they landed.
Plenty for the media to have some fun with though. I'm sure the truth will come out in someones book in a couple of years.
Probably not if the mission was to return them alive. 
