Bear with me: in a sense, I agree with him. I'm not sure whether I can explain this properly.
One of the things that has bothered me most about the destruction of the WTC was its spectacular grandeur. The scale of the catastrophe was terrible. The enormous balls of fire, the gigantic columns of smoke, the way in which the collapsing buildings flowed like liquid down their own sides lent a perversity to the act that is unmatched by many disasters with larger death tolls.
It was mass murder as performance art, which is so much worse to behold than simple mass murder.
It reminds me of the legend of the woman who made lampshades with the skin of Jews slaughtered in the Holocaust. When we think of such a thing, it's comforting to picture the lampshades as looking like something out of the Flintstones, with ragged edges and perhaps bloodstains, the product of an uncivilized brute. How much more awful it is to picture instead a really pretty lampshade, gracefully executed by a skilled hand! Artistry is something that the civilized mind just does not want to associate with barbarism. When we see them together, our minds recoil.
Hannibal Lecter doesn't simply tear out someone's liver and gulp it down raw like an animal. No, he eats it at a table, with fava beans and a nice Chianti. The garnish amplifies the horror of the act.
If the fall of the towers hadn't been so beautiful, for lack of a better word, the tragedy would not have been as horrible.
The collapse was spectacular (my preference) because the towers themselves were spectacular, as was their manmade environment: the Island of Manhattan. The world was the audience for the collapse thanks to worldwide television a product of (mostly) American technology, energy and business acumen.
The destruction of the towers was as much "art" as was the Talibans' destruction of those beautiful Buddhas in Afghanistan.