This is a classic truther misconception, and would benefit from some further analysis.
Building collapses can be divided into classes, based on their initial cause. One of these classes is collapse due to fire-induced structural damage, another is collapse due to explosive-induced structural damage, a third is collapse due to earthquake damage; I'm sure there are others. We could use the analogy of classification of animals into different classes; birds, mammals, reptiles, fish.
Within each of these classes, we can define specific features of the collapse, and determine the general details of the collapse mechanism. These would include things like top-down collapse, toppling, bottom-up collapse, or other general features. In the analogy of animal classification, we could represent these as different families; carnivores, insectivores, cetaceans, and so on.
Next, we can start looking at the fine details of the collapse; what specific structural members initiated the failure, what was the failure mode, how did it progress through the structure. We could represent this as the genus; for example, dogs and foxes.
Most of the criticism of the NIST report focuses on the last of these levels - the specific, detailed failure mechanisms. To use the animal analogy, there's an argument about whether the creature we have before us is a dog or a fox.
RedIbis's argument is akin to saying that, if we're not sure whether it's a dog or a fox, then we have to consider the possibility that it's actually a fish.
Dave