Pardon Our Dust.

[klange]

Set it up so that he only has the pistol once you hit the trigger volume? I think people tend to kill him for the ammo, so that might work?

Just make him have one shot in the pistol. That way, if people kill him for the ammo... well, they're not going to get much, and it also makes sense when he kills himself.

e: I should note that the player should see this as reason not to bother killing him on a second play through.