As I mentioned, likely because it was a data point that crossed city, county, and state lines. I can't think of another data point that provides that type of insight across such a broad swath of the population at a specific point in time. If you have some, please provide, it would make for a richer data set.
> The best thing would likely be to look at a matrix of policies for each state to identify potential impact from a specific policy over time and in combination with the other factors.
Plenty of that analysis is available, unfortunately the results don't penetrate the echo chamber. Here are a few [1] [2] [3].
[1] https://www.ojp.gov/pdffiles1/nij/grants/254669.pdf
[2] https://www.rand.org/research/gun-policy/analysis/stand-your...
[3] https://www.bu.edu/articles/2019/state-gun-laws-that-reduce-...