It's another indication of how Al Qaeda operate, it's basically how most non native forces control any group, terror.
Al Qaeda did similar things in Iraq, that's why the insurgents turned against them.
You need to learn to differentiate between Al Qaeda, and Muslims in general, this was a show of force to tell the people what will happen to them if they resist their presence.
They'll pick whatever pretext they like, doesn't mean they're right, the U.S shot a load of unarmed people on the pretext that you can't surrender to a helicopter.