I don't know why, I just know that he does:Building designs are unique and likely initial damage is unique.... Why would you expect "prediction" and how useful would it actually be?
Expectations: We expect, that we will be able to simulate failing building structures under hazardous impact to a degree that allows predictions, what building parts will resist the impact and where falling debris will accumulate. In a best case scenario the simulation will indicate where spatial pockets will be likely to be formed, that allow victims to survive.
Counter question: how can you use a software/method to answer engineering questions that has not been shown to correspond to the real world?How can you predict for a specific building if your calibration is post hoc?
My main point is, the WTC simulation gets youtube views, but it doesn't make any engineer trust Bullet Constraints Builder.