I would be really impressed if it were possible to control for the differences that would occur if one state did a very good job tracing potential cases and then testing them (Massachusetts), versus more ordinary blanket efforts elsewhere.
I think we will see the overall work when we look at deaths. It is lagging though.
The author needs to re-run the analysis using only deaths, or deaths plus hospitalizations (if those figures are available). I fear that all the model reveals as currently written is how well states are getting a handle on their testing, and paradoxically showing states with better testing as worse off because of the growing number of cases.