The dudes' reaction to the accident

Spoiler alert.
Anyway -- perhaps this point is too obvious to make, but I don't find the military guys' reaction to the death of their friend remotely plausible. I understand they would be sad, and maybe a little angry, but it's very clear in context that their buddy was the aggressor, and there is no evidence that the woman was some sort of depraved person who killed him for no good reason. One doesn't go from beer-drinking cute chick at a campfire one minute to deranged killer the next. That being the case, the normal reaction of those guys would be to just call the police (whenever they can do that) and move on. (And even if one dude went nutso, his buddy would bring him back to reality.) (And I know that they are probably not thinking rationally -- but how the heck are they ever going to take him back and tell his family and give him a burial etc.? His body will be rotting for a few days on an island and they'll have to explain that head wound, and the rot etc... Not to mention possibly the three other corpses on the island.) The idea of taking vengeance is absurd. If these were hillbillies or mutants or victims of radiation, then this reaction might make sense. As dumb as people (and guys) can be, this just goes beyond all normal human reaction. As such, the film loses all credibility here. They could have tweaked this a little to make the overall story work (i.e. three chicks hiding from some bad dudes on an island), but as-is the story line is just bizarre.