We should stop talking about "lockdowns", and possibly never should have thought that way. The question is over restrictions, WHAT restrictions should we have, what alterations to usual way of doing things.
For instance, do you know Sweden, all along and still now, was in fact prohibiting gatherings of over 50 people, with criminal penalties for violating? Schools for children over 16 were closed. Social distancing was encouraged. Sweden didn't actually do particularly well -- although they have done BETTER than the U.S. in deaths per 100k population. But however poorly or well they did, contrary to the narrative, they in fact made major changes to social life, and in the end may have controlled social distancing BETTER than the US! (through a combination of legal restrictions and voluntary compliance, compared to the U.S. piecemeal, ever-changing, lockdown-then-nothing low-compliance environment).
So it is definitely a problem to think that our choices are a total lockdown which can reduce all risks to zero (unsustainable and not actually POSSIBLE; quotes about "which grandparents are going to die" suggest that if we do things right it will be no grandparents, which is unfortunately not true) -- and doing virtually nothing except maybe some half-hearted mask-wearing, which will result in years of ongoing massive illnesses (including possibly long-lasting chronic illness) and deaths.
In fact, we have to figure out how to do restrictions RIGHT. restrictions that are sustainable for the long-haul (becuase in fact this is going to be something we're dealing with for years, there is no deus ex machina vaccine miracle that will put things back to how they were), and that optimize for minimal infection with maximal social life. (In normal life, I have trouble explaining what I mean by 'optimizing' like this, it's nice to be talking on HN in an engineering culture that will immediately understand what i mean).
The US doesn't seem any closer to being motivated to do that though. And I"m not sure this letter actually helps,this comes across as just another allegience in the "do everything or do nothing" weird public health culture wars, which are not serving us. (For instance, "Herd immunity" is mostly not a useful thing to be thinking about here, and mentioning it just seems like signaling a 'do nothing' allegiance or implying that intentionally increasing infection rates is somehow a good thing, which it is not, unless you like years of ongoing chronic illnesses and deaths).