Listen to the whole section; here’s a longer excerpt:
Thornton was clearly comparing wind load with the relatively minor impact of an aircraft. He said that an aircraft couldn’t knock the building over, and indeed, the 9/11 impacts did not.
You quoted selectively, leaving out the following:
– “it could affect localised structural elements, it could knock out a column, it could be some damage”
Yes, in 1988, when the video was made, Thornton is being loyal to his profession, playing down the likely effects of an aircraft impact, and not being rude about another professional’s work. He’d expect the same in return, of course, and Skilling would be unlikely to call Thornton’s designs “overweight, heavy constructions with masses of unnecessary stone and concrete”.