Nothing puzzling about it. That building was severely damaged and whatever else Silverstein is, he is not a demolitions expert and the term 'pull it' is not a demolitions turn. You are mindlessly quoting a misleading quote.

Meanwhile I've unearthed and re-watched a NOVA episode "Why the towers fell". It is utterly convincing, and has nothing to do with any government reports. It was put together over the year after the disaster by structural engineers and included some touching interviews with one of the creative designers of the project.