He doesn't do it for fun... He's a coward. He'll do whatever benefits himself the most. All he cares about is his awful family.

[Mahiru's head gets sore just thinking about that guy and I finally remembered the other reason why the infirmary was a good idea: Mahiru never took her bandage off all day yesterday. It's all caked red, and she turns away as she puts a new one on.]

But he can't exactly open fire on everyone here. He has to play nice... and have an alibi... if he doesn't want to be executed. He's probably a regular player with no motivation to murder after all. That's how the evidence looks for now. I don't want you to lead a witch hunt just because I knew him and he was rude to me before this situation.

[And she definitely means this situation, not that island. Dipper can take that description of his conduct as he will.]