She's not so bloodthirsty or so lost that shooting her only options for human contact seems the most viable course of action. The gun's clipped to her side with a nod, her own hand lifting briefly in a truce before—

"Cortana?"

Sombra blinks, mulls it over for a moment before figuring that despite the difficulties in navigating transmissions, equipment or just plain space in this nightmare, Cortana can probably jump to anyone that's close enough on a whim. Plus, she was resting for a while...

"Sounds like she trusts you, then." Which means that after a beat, Sombra adds her own introduction, belated and unecessarily: "Azúcar."