It just doesn't seem sustainable either way though. You can cancel games for two days while you wait for everyone to be tested twice or you play through but then cancel them after they get tested twice along the way. If the tests are positive there's no difference. Option 2 prioritizes playing baseball, Option 1 prioritizes health. It's all well and good that most of these guys are asymptomatic but not all of them have been. And for the clubhouse attendants and umps and coaches and other personnel to also be at risk is just wrong.
Heck, for all we know the Marlins caught it from the Phillies, who caught it from Bryan Price. I assume testing won't suggest that, but we'll have to see.
The games are cancelled partly for PR reasons, but also they have decided yesterday's game was high-enough risk that now both teams are in isolation. I believe the city of Philadelphia may also be involved. Ultimately, this could be shut down by cities or states, not MLB.