The entire study does not even pass the sniff test. Viruses are not magic. We pretty much know how they are transmitted. So unless you can show me some theory that explains how viruses can travel long distances all on their own then stopping people from moving about stops the virus from moving about. It is really that simple. The only thing this study might be able to show is that a large number of people didn't comply with lockdown restrictions, or that the restrictions we put in place were not strong enough.
As I recall they would report statistics like the "average number of daily contacts" of people, and you could see those decline in line with restrictions. Of course you can't ever get it down to zero, and there's a price to pay in terms of other health problems and economic damage, but it's a trade-off. One can absolutely argue over where the 'sweet spot' is, especially when you add in other measures like masks, ventilation and vaccines.
