if you're going to self isolate anyway there's not much point in testing I suppose other than for statistical purposes and at this point my guess would be that testing people on the frontlines is more important.
If he tests positive then the self quarantine he is under would expand to his contacts since Sophie returned.
What "frontlines?" Everywhere are "frontlines" at this point.
healthcare workers, public service workers, food, transportation, pharmaceutical and so on. People who need to definitely know if they are sick or not.