While they still will have to isolate for a bit, just because they tested positive doesn't mean they have active cases and are "spreaders." There are those in the medical community who feel that the disease is much more wide-spread (up to 25% of the population) since the 80% of those who get it have insignificant to no symptoms and often don't even know they've had it and are never tested.
Roughly 26 million tests (which doesn't translate to anywhere near 26 million people) have been given with roughly a 9% positive rate. We know that there are a huge chunk of folks out there that will test positive but are likely done with their course of the illness.
I'm not going to question the folks that make these decisions, and I'm not trying to make a political statement, but this country will be in worse shape than the days of the Great Depression if we hole up and wait for a vaccine. We need to manage through the situation with appropriate caution. Sports is a good place to test the waters.