Lt Hendricks was also in the loop.That is why he only died at the end of the battle. He got killed a lot of times too, but always came back when Rita too died and the loop reset - or when one of them successfully killed the server mimic with both of them surviving. He didn't seem as skilled as her, though, so he probably got the power relatively late and did not get too many attempts with it.
- Or, if true maybe he realized Rita was looping and he knew that he had to die for her to escape. Though, this is doubtful because Rita didn't discover this quirk of the loop until she found another looper.