Fair questions. What fatality rate are you expecting for not-at-risk people? Is that risk of death acceptable to you? What risk of death should I expect, I'm a healthy 47 year old male. Is it 0.1% or 0.01%? The difference between those two matters to me and the research isn't clear yet as far as I can tell.
By doing a bunch of the steps implied in the document my chance of surviving is better, by keeping the infection rate in the populace lower so that I'm less likely to get infected and die before the vaccine arrives.
Whatever number you arrive at is your concern. You want to shelter in place go for it. What I don't want is the government shutting down everything. Leave it to the individual.
This interesting to think about, but truth is a lot of at-risk people still need to be out there. Take all the workers for critical infrastructure, businesses, hospitals, etc. They need "the outside" to be as clean as possible too.
Consider an emergency, where someone who wants to shelter needs to go somewhere (say, the hospital, airport, etc), or receive someone at their house (say a doctor, technician, etc). Or consider groceries and other needs that come from the outside but are brought to people sheltering. You want "the outside" to be as clean as possible in those cases too.
Perfect isolation from the outside world isn't possible, but with a general shelter-in-place, there's fewer chances that "the outside" is virulent. Very similar to herd-immunity and vaccines.
Something I thought about the other day that I think puts some of this in perspective:
The population of the US is ~300 million. The average lifespan is ~80 years.
We have a growing population, but supposing we had a stable population, that would require a bit more than 3 million people to die each year.
Basically my point is, in a stable situation, that order of people will already be dying yearly.
I don't know what the actual numbers are for the county, but basically since people live less than 100 years, if we had a stable population (which at some point we'll need to return to), then roughly 1% of the population needs to die every year.
Those numbers are unrealistically high, but even so I wouldn't blame the government for them. If Wuhan hadn't set a bad example, I doubt anyone would have even considered universal house arrest as an option in the government's toolkit.
By doing a bunch of the steps implied in the document my chance of surviving is better, by keeping the infection rate in the populace lower so that I'm less likely to get infected and die before the vaccine arrives.