Syrian rebel groups are more or less in unanimous agreement about not liking ISIS, and excluding them from both the ceasefire and peace talks was pretty uncontroversial. The question of al-Qaeda’s affiliate, Jabhat al-Nusra, is another matter entirely.
The Nusra Front has been used as a front-line fighting forces in the Syrian rebellion for years, and has close alliances with several “moderate” rebel factions. Though it’s unthinkable in practice to allow al-Qaeda into the peace process, let alone to be part of the post-war government, many rebel groups feel clearly beholden to them.
Other factions, however, aren’t so sold on Nusra, believing the group’s ideology makes it unsuitable for postwar Syria, and its involvement in the war little more than a temporary convenience. Some are openly talking about the post-war unity army being able to wipe out Nusra in short order.
That may prove overly optimistic, however, with the Nusra question splitting the rebels heavily, and getting seriously in the way of the peace talks, as many don’t want to negotiate a settlement that will ultimately cut their al-Qaeda allies out of the picture, and even if they do end up making a deal, expelling al-Qaeda from its territory is going to e no small task.
The non-Salafist rebels surely can’t want a resumption of open warfare with the Syrian government and its allies. They know what Russian bombers can do to them, and they don’t want to be surrounded and besieged in Aleppo. They are going to have to deal with al-Nusra sooner rather than later to prevent the ceasefire from collapsing.
Not all members of Jabhat al-Nusra are even Salafi. There is a secular fighter who joined Jabhat al-Nusra because he liked the medical care it provided. Many members of Jabhat al-Nusra dislike the “Salafi” policies of the Islamic State including its banning of tobacco, etc.
It’s not just about individual members of ISIS and Al-Qaeda. It’s the institutions themselves that drive militant behaviour. And those institutions are a brand of salafism/wahabism mixed with elements of Marxist-Leninist revolutionary ideology. You want to know why ISIS destroy historical artifacts? The Saudis have been doing it for centuries. That’s not an accident, it’s wahabism. Likewise, Saudi thinking on Shia Islam is not new at all – and Al-Qaeda has done it’s best to provoke sectarian conflict with its continuous stream of suicide bombings in Baghdad.
And yes indeed, former Iraq Baathist generals have helped ISIS administer their Caliphate on the Euphrates so it can govern as a state – with the same social policies of Saudi Arabia. But the civilised world will not accept it.