Creative Speculation

Structurally, that is a separate and independent building. The building that collapsed did so completely, up to an "expansion joint" between it and that building. The purpose of expansion joints in large reinforced concrete structures is to allow the separate structures to expand and contract independently of each other, and thus not crack the concrete. It also saved that building from the progressive collapse, but it doesn't save your collapsed argument: It was a gravity-driven complete collapse of that independent structure, and you refuse to even think about the simple explanation that real experts have for it.

Not surprisingly, you also dodged the question I asked you about Chandler's "uniform acceleration" nonsense. How convenient.