The Giant Impact Hypothesis describes that Earth's moon was formed from collision between a proto-Earth and another Mars-sized object. This collision ejected mass from the Earth into orbit, whereupon the material formed an accretion disk, and eventually, our Moon.
The way I understand it, in order to place an object into an orbital insertion around Earth (from the Earth), two impulses are required. The initial impulse is used to lift the object out of Earth's atmosphere, on a parabolic/elliptical return-path. A second impulse must be applied in order to circularize the object's path and create an orbit.
I also understand how Gravity Capture works. However, since the aggregate matter used to form the moon was ejected from the Earth, I don't believe that this applies.
So how does the Giant Impact Hypothesis reconcile these two seemingly conflicting arguments? Is it really possible to blast an object into orbit without any other influences?