Unless there is some proof otherwise, I'm gonna assume it was genuine performance art.

Taking what the author says at face value, the goal was "See what the public would do to a human if given tools and unrestricted access/allowance for 6 hours", and the conclusion is up to the audience and future viewers/readers, rather than the author trying to steer people into some predefined conclusion.

One way you could see it is "all humans are inherently evil" but that's not the way I see it, as the audience seems to eventually be split up in one "nice" group trying to stop the "not nice" group from acting out.