It's the correct way to do a rescue, sure. But it's definitely not fast. Not enough. Shepard is incredible, indomitable, but she's human. Humans have limits. That brief little glance of theirs is enough to prove it. So he double-times it. He hoists the kid up, to flat-out carry them out of the rubble. Less chance of the kid catching an injured leg on something, too.

Once that's in hand - har har - Garrus just books it. A flat-out sprint the last couple yards to the edge of the rubble.

"Clear!" he shouts, hooking a free arm around the woman too. She's too close to the rubble. When Shepard drops the lift, there's going to be fallout. Not flying debris, no, but dust, at least, and it might very well jar a few things loose. Shepard can handle it. But a civilian?

He gets the woman clear, sets the kid near her - ready to run back for his Commander if need be. "We're good, Shepard!"