I hope he's right but I think he's presenting this as a stronger case than it really is. Facts 2-5 I don't think there's much to disagree about, but the crux of everything is in Fact 1. He's using the Stanford study to come up with the .1-.2% fatality rate. Interestingly - he closes his argument by saying "Let's stop underemphasizing empirical evidence while instead doubling down on hypothetical models." But that fatality rate itself is not purely empirical evidence - it also has some significant projections.
Reading through that study - they recruited 3300 participants for antibody testing using Facebook ads, and got 50 positives (1.5%). They then weighted (i.e. projected) the sample "to match Santa Clara County by zip, race, and sex" and came up with a prevalence rate of 2.81%. They then further "adjusted for population and test performance characteristics" to come up with a prevalence range of 2.49-4.16%. They then applied (another projection) that rate to the total population of Santa Clara county (1.9M) to get an estimate that 48,000 to 81,000 had been infected. They then take the official death count from Santa Clara County (50 at the time of the report) and project that the total death count through April 22nd would be 100 (for what it's worth - the official death total there is 95 as of today, so that's pretty close). 100 deaths out of 48,000 is .2% and out of 81,000 is .12%.
All of that may be 100% correct. It could also be very very wrong. If recruiting participants through Facebook ads disproportionately attracted those with covid symptoms who wanted to be tested (which seems at least plausible) then that would skew the prevalence rate - possibly by a lot. And since everything else is based off of that, that potentially completely changes the conclusion. They are also only using the official death count to determine the overall mortality rate. Nothing inherently wrong with that but in concluding that the actual prevalence is "50-85-fold more than the number of confirmed cases" it seems odd to then assume that the confirmed death numbers aren't at least partially under-reported as well.
Hopeful that numerous other similar studies are being conducted right now and if their results will agree. I would definitely agree that if the fatality rate is in fact .1-.2%, then yes the world has over-reacted. Although, if 2/3 of the population of the US gets infected (a good estimate of what we'd need for herd immunity) we'd still be looking at 200k-400k deaths from that.
