I believe he's trying to say that, although death's going to happen, no one should be in charge of whether someone should live or die. If such power is asserted, it becomes attributed to that person and history has shown, currently shows, and will show that power corrupts.

Unfourtunately, though, it was right there in front of him. Nguyen knew that what he did was greatly illegal and that getting caught would result in the charge that was executed against him. As pure as his motives were, I know that there might have been better options for him to have chosen. So, in review, killing=bad but Nguyen knew it would happen and did it anyway.