Is there ever a point at which quarantine is the only effective option?
Theoretically, I suppose a quarantine could be considered. The problem is, and don’t misunderstand this, the problem is the Constitution. We have rights of free movement, equality of citizenship, full faith and credit, open commerce, etc. between the states. That’s a nontrivial barrier to implementing quarantine. Only if CA ever fully detaches from the mother ship and becomes it’s own country would quarantine have a shot at being meaningful.
But realistically, we would have to get a lot better at quarantine for even that to work. Witness our trouble with Mexico. And even Canada, as as a preety good neighbor on many levels, imports way too much liberal-think.
So I think quarantine is simply too passive. You can only hide out for so long. If conservatism really is the better idea, and I believe it is, we need to keep on exporting it from whatever consolidated centers we can put together. And if we are exporting, we are not quarantining. As they say, the best defense ... wait for it ... wait for it ... is a good offense. California is no exception, IMHO.