They're not exactly good people from what I'm reading about them. They might actually be more authoritarian than the Assad regime, but as long as they don't somehow take over the government (which would be a tall order for a group that only holds power in the Idlib Governate, the province to the west of Aleppo) they can still be useful.
There's a chance that they could destabilize the situation enough where more moderate elements of the opposition forces start taking action as well to try to prevent extremists from seizing power.
Fight - You will win! Slava Ukraini!