Well, no. The US blocked everyone coming directly from China, or who had been in China for the past 14 days, regardless of citizenship, with exceptions only for its own citizens and green card holders and a few other categories, who were still allowed to fly directly from China. Where the US screwed up was in not requiring mandatory quarantines for returning US citizens/green card holders on arrival. But while the US was too lenient on its own citizens and other citizens coming from places other than China (including Italy/Europe), China's approach is also ridiculous. While I can understand banning everyone except their own citizens from epicenter outbreak locations (such as the US) at this time, not allowing people in from New Zealand and other places that have effectively been able to suppress their outbreaks (even if they're willing to submit to a 14 day quarantine to make extra sure) makes no sense.

SARS-CoV-2 is a virus. It does not care where you're flying from or what citizenship you hold. It will infect anyone (actually, I should say anything, since cats and dogs and other animals can apparently get it too) with ACE-2 receptors.