What is the human-sized biomechanical thing attacking Shaw?

At 11:39 of the super slo-mo trailer you can see a human-sized character attacking Shaw. This character is obviously human-sized, but it has a pattern on it's legs very similar to that of the blue guy in the chair chamber. Is this David having been commandeered by the SJs/Engineers and "modified" by their technology? Or is it the mutated crew member? Could there be a mechanized component to his mutation? What do you guys think?