If the artist feels a certain aspect of the work is integral, that can be important. There are probably a lot of people who would be influenced by an artist's threat to declare a work "not art," especially if it is his own work. I think that's all he's saying: "I can't stop you from breaking the terms of this contract, but if you do the work is dead to me."
can't a work of art remain a work of art - or even take on new artistic meaning - if it's declared 'not art' or 'dead' to the artist? Especially when it's entitled 'a tool to deceive and slaughter'!
For instance, if someone was found brutally bludgeoned to death with said black box, this changes the context and thereby completely revolutionarizes the artistic and cultural, not to mention physical, impact(s).
Sure, it all depends on what's most important to you. The important thing to realize is that the art/not-art distinction is completely fabricated -- everyone means something different when they say "art."
