“This true infection count was so high that it would drive down the virus’s local fatality rate to 0.12%–0.2%”
The big problem in claiming such a low number is that it is already EXCEEDED in part of New York city, simply by dividing the number dead from Coronavirus (in Brooklyn and Queens) by the TOTAL number of people who live there. In other words, even if you assume that EVERYONE there has been infected, the death rate is already above those numbers...and of course still climbing.
There are 23,282 dead for Covid-19 in NY City. 8,399,000 people live there. The number of dead divided by the number of residents is .002772. Why are you limiting it to two boroughs?