As noted further down in the article they handed over a quarter of their weapons in return for "safe passage". That said I wasn't there so I don't know. Yes 6 new Toyotas were handed over.
There is more to this than meets the eye. There would have been an assurance that they were on their way to fight Assad only of course. Deals like this happen from local commander to local commander ......... with the possible exception of the YPG (but not the PKK/HPG) there isn't the centralised command and control that outside observers may assume.
A reason that al Nusra is considered a more important target than ISIS is that it comprised largely of Syrian's and it controls local respect and support on the ground. By contrast ISIS is split morebetween Syrians, Iraqis and foreigners. The local Sunni Arabs absolutely hate foreigners (would be jihaddis') coming in and telling them what to do in their own country. Therefore a key risk for both Russia and the US may be that the local Syrian's in ISIS could defect to Al Nusra.
Although Al Nusra receives direct support from Turkish funded militias (with the full knowledge of the sponsor) the group also presents a higher risk to Turkish and Saudi interests than they know .... because there is no way that any US Administration will have anything to do with and Al Qaeda affiliate. The US may support other Islamists but never Al Qaeda. The 9/11 veil means that American supporting al Qaeds will be branded a monster forever at a level far worse than what Bennadict Arnold got. The US would even support its arch enemy Iran over al Qaeda ... and if push comes to shove that is what will happen.
With Al Nusra being a key thorn in the side of the US/Saudi coalition that previously included Turkey, why would the Russians pick on al Nusra??? Maybe the Russian objectives are nothing more that a tactical land grab? Attacking al Nusra certainly helps the Kurds .
