These dudes were saying that China could have prevented the pandemic but they choose to let flights out of Hubei a day before the quarantine.
A cursory look through Wikipedia shows that international cases were confirmed well before Wuhan was locked down. So my workmates are full of shit, right? Sorry, I don't follow this thing closely.
Sorry for making you have to listen to more anti Chinese bullshit.
They could have sure, theoretically, but they fucked up in risk estimation. But also not a single country in the world would have closed flights over 1000 cases of a novel pneumonia in winter, when this could have been actually stopped, plus who knows how many assymptomatic carriers there were