If you're going to drop links to Reason at me, you should also take a look at https://reason.com/2020/03/11/would-italian-style-lockdowns-... which is less recently published but addresses the question of a "China-like lockdown" more directly, rather than simply looking at questions of "can the government close my favorite bar?" It almost certainly can close the bar, but personal liberties — the freedom to not be under some sort of house arrest — tend to get a lot more scrutiny than commercial activity, for good or for ill. Where specific quarantine powers exist, the language authorizing these quarantines often hinges on whether the persons quarantine are actually a substantial risk to public health; here, we are talking about the freedom of movement of ~7000000 people, due to the (known) infections of approximately 200. Just by these numbers, this is an exercise of quarantine power that is without precedent.