Personally I don”t see anything wrong with continuing to fly, provided one take those basic precautions as Steven mentioned. Individuals should make their own decisions based on any additional risk factors they may have, of course.
Actually, it seems like a pretty great “low risk of exposure” activity to me though, especially given how many things have closed down.
For what it’s worth, I fly at William’s Soaring in northern California now, and they are still operating.