Fresh air is good for the health.
But if you are weakened by another illness, stress, other underlying conditions then you definitely should save your strength especially if you are in a high risk location or occupation or anticipate contracting the virus. Most (80%) have mild symptoms no worse than a cold but the percentage that get severe symptoms is high and more severe than most illnesses we have to deal with in this amazing age of health..
So to each there own analysis of their situation- will fresh air and physical exercise do you good vs. Does it gain you extra exposure or potentially weaken your immune system.
Certainly don’t over do it (pot calling kettle) otherwise in general if it is permitted then a ride outside is even better than inside.
As they say on Zwift- “Ride On.”
Whether in or outside my shirt says “it’s not a race” on the front and “It’s a race” on the back.