It is interesting to note that although he was not born in the Enclave, they still rescued him and used his expertise in robotics. This, along with the fact that he wears a Pip-Boy glove, hints that he may have originated from a Vault, and is considered by the Enclave to be a "pure human". It is equally possible they just use him because no one else at Adams Air Force Base has his knowledge of robots.
Who Dares Wins: Stiggs approaches you on the lower level of the mobile platform and asks if you are going to hurt him. If you let him live, he can give you some information about the crawler. A dialogue option opens up if you have the Robotics Expert perk, where your character speculates what system the mainframe uses. He will compliment you as finally being someone who understands what he's talking about, and says you'd be able to reprogram the robotic and turret systems inside the base so that they will target the Enclave instead of you.