The 100km clause is a reason to pin lower. This is a really, really weird definition of "large-scale rioting" that actually is more geared towards the question "will there be a really large riot somewhere in the United States in 2020" than "Will the US see large-scale rioting in 2020".
Back-of-the-envelope would have the building total at 880. Obviously cars/police stations/skyscrapers are using current math, per the spreadsheet, and don't have to be adjusted.
@JonathanShi Ah, thank you, that math does seem to put things into better perspective.