Why the fake accidental gun discharge situation?

Early in the film a guy falls over with a gun on his back. For some reason in post production they have decided to portray this situation as an accidental gun discharge. It looks like a visual effect, it sounds like a post production audio effect and the reactions of the people involved are completely inconsistent with a near death experience.

I find the whole event so jarring in a documentary and it completely skewed the way in which I watched the rest of the film.

I'm not angry, I'm just baffled why they did this.