I've been thinking about this ending lately and I honestly don't believe that the deputy killed everyone in the truck.
For the Resist Ending I wanted to see the worst but for the Walk Away ending I didn't feel as though anything bad happened.
I think that the deputy just had something like a bad trip and that was it.
The whole point of Jacob's training was to kill Eli which already happened.
Now you might bring up all the people "killed" in the training but some fans noticed that you don't actually kill any of the whitetail members until the forth trial. I think that the whitetail members start bleeding out and dying right when you get into the bunker.
I even think that during the wolf beacon segment that the whitetail members just poof away.