Has anyone met that challenge?
Perhaps there is no
definition of "performance art" ... that also excludes acts of terrorism. What you wrote in the OP:
I fixed a liiiiil sumpin for you in blue, and otherwise added a little to the definition to make it what many people would understand to be a good definition of terrorism.
So maybe on some level it is useful and appropriate to describe terrorist events from an art critic's point of view. However, in a very important sense, that is not what truthers are doing with 9/11:
9/11 truthers deny the identity of the artist, and consequently their critique addresses neither the actual performance nor its intended or actual impression on the audience.
To me, it seems more fitting to describe what truthers do as some kind of art. Sometimes perhaps in keeping with a popular genre of fiction that is loosely based on historic episodes and figures but spins invented stories that might fool the less history-savvy audience into thinking there actually was a woman on the chair of Peter, or a math code in the bible.
Another idea: No-one has yet discussed the question of who the intended audience is of
- performance art
- acts of terrorism
- art critique
- 9/11 trutherism
In the minds and professed opinion of their authors. all four are directed at a more or less general public, but I suggest that there is good reason to think that all four have mostly their peers in mind:
- The general public is largely ignorant of and uninterested in performance art, while performance artists go out of their way to consume as much performance art as they can. Performance artists compare themselves with each other.
- I can't find it right now - I think I have it bookmarked on my other computer - but there is an interesting thesis by a fellow named Max Abrams (or similar?) who has studied a number of terrorist acts worldwide, their professed intentions, and their actual results, and he concluded that terrorists are generally less motivated by the chance to effect political chance and redress social grievances, and much more motivated by the expectation to gain prestige among other terrorists)
- Who reads performance art critiques, except performance artists and other critics?

- Truthers circle-jerk most of the time
Yep, some of that is controversial if not adversarial, and none of it documented. Just some ideas.