it was a very unlikely possibility even in month 1, as i said repeatedly at the time. the global system cannot shut down that immediately. it's a cruise ship, not a skiff.
we know that covid is highly contagious compared to other novel diseases, that it remains on surfaces for quite some time, behaves as an aerosol in certain conditions, etc. really, it is a symptom of our globalized system as much as inept government responses.
it's impossible to expect all flights, trade, freight, shipping, etc. to cease because of a (then) small outbreak. even if the medical community were making very loud and alarming noises. it's just not realistic. it's not a happy result, it's not an ideal description, but things are of course complicated by reality.