I think the film exists simply because the man can't choose himself. This conceit brings about two intriguing elements:
People have an intrinsic desire for "justice" in the form of eye-for-an-eye - but this becomes emotionally incoherent when the victim is not around to have this desire for "justice" satisfied and the pain of those remaining is not one of gross injury but of loss. As such, death seems "too easy", and won't be an equal punishment for anyone remaining. This is because of two things:
1. Retributive justice is a selfish pursuit, and its toxicity is obvious when recognize how a desire for retributive justice can accomodate the death of an innocent person without purely being revolted at the loss of the innocent person, whose life becomes merely an instrument in order to spread misery in kind.
2. In a world where this "punishment" is thought to be "just", it is obvious that the world does not become a more just place when "justice" is carried out. In that world, as in all others, justice is never truly served by punishment. The victims will never regain what was lost. This brute fact is not easy, and it is easier to lust for revenge than to simply accept that what is done cannot be undone.
One can imagine a better world where no person seeks this form of "justice", and this film would seem ludicrous and benign. We certainly don't live in that world, though - where Palestinian civilians are being murdered by snipers in Gaza because they are protesting their captivity and servitude for the crime of being born in the wrong place - and the killers are being praised for their "restraint". The "justice" of the film seems quaint by that standard. What a shame that a horrible, mind-numbingly absurd, pointless, and destructive form of "justice" is an improvement in the world we live in.