About the necklace, you cannot know, as we dont know the animal itself. I don't think it represents sadism, though we don't know what kind of creature was it. A wolverine is smaller than a wolf, but far more dangerous. As I that wasn't even made by the hunter by the way.
In the metro, those people did pose threat to the hunter. They wanted to attacked him, and did so, and although just one of them couldn't kill him, the whole pack could finish him. He had to make a decision, and he thought they weere dangerous, so they had to die. I didn't say, they exactly know what's a threat to them. But they try to 'categorize' (sorry, it sounds dumb
) and act according to this. Little guy who's just watching, no threat. Bunch of 'ready to shoot the mofo' threat. It's up to the hunter's decision, a subjective choice. They are not the same, but if they make a mistake, they pay for it. And I think shooting the little guy would be one.