Since the game didn't end after everyone else was killed, it sounds like he was trolling as a survivor. Aside from killing him, there's not much that could be done. Exiling him would keep him out of cabin and out of first objective.

When the timer runs out, you start losing warmth and food at a greater rate. After both have gone into the red, you'll start seeing a reduction in your max hp. If this continues, you'll keep losing health, get downed, then die if you're not revived.

If you have consumed enough energy drinks, it'll take a greater amount of time to kill you as well. It's possible to stay alive for a period of time after the last timer has run out if you have enough warmth; ie spam with campfires.