It's Because they were evacuated e.g. from Cruise ships with other symptomatic patients, and were quarantined + tested, it's a CDC standard protocol [2]. They even put one of them down the street from me as we speak [3]
But that story (1) says they had sore throats. They do not consider a sore throat a symptom? So this is the new CDC? Ignorance is strength? War is peace?
Where did you hear this? Why would these people even be tested, much less diagnosed, if they are not showing symptoms?