Oh, man. I killed Boyd. I've been killing every NCR I meet. And the 'unlock' won't work on that door either, it seems. That Legion dude is gonna starve in there now. :(
I can't seem to find the item code for the key which opens the prisoner cell in Camp McCarran Terminal... you know, the one with the Legion-looking prisoner whom can be views through an irregularly shaped clear window.
Google searches, including of this forum specifically, turned up...