Pretty much the only way that people from Coronavirus infected countries (China is the only one where it is widespread) are getting to Boston to go to PAX would be via airplane, and most of the major US airports, including Logan International Airport in Boston, are screening for Coronavirus with thermal scanners. On top of that, the US is not allowing foreign travellers into the country if they have been to China since the outbreak began. In other words, there isn't much risk of catching Coronavirus at PAX East. Sony has plenty of US based developers and execs who could have attended, their headquarters are in California now afterall, not Japan.
You do realise that the thermal scanners only work once the infected ppl have actually gotten sick and are showing signs of having a fever, which can take up to like 10 days?
I am pretty sure they are only stopping travelers who have been to Hubei province, not the whole of China. That said, the virus has spread beyond China. And again I ask, are all the exhibitors at PAX, and the visitors only from Boston? There is no guarantee that a visiting person could not be infectious by the time they are attending PAX.