The main concern with such techniques, is insuring that the non-shooting hand remains unshot.
Usually, these techniques involve the shooting being done from a one-handed retention position which pulls the gun in tight against the body in a comfortable position about midway up the torso. It's intended to make it much more difficult for the attacker to access the firearm.
A common approach for protecting the non-shooting hand is blocking out areas for it to operate that won't ever be covered by the muzzle.
More conventionally, shooting with one hand and defending/striking with the other involves an empty non-shooting hand. It's used to block blows to the face (hand and arm are high and out of the area covered by the handgun) or to administer pushes/strikes high on the target.
What she's suggesting isn't really terribly off-the-wall, but it's not a basic technique. She should really get some instruction from someone who teaches techniques similar to her intended approach.