Less likely, maybe. But, what happens if one of them touches a surface that someone else has infected? People are infectious while showing no symptoms. They are elderly, at risk, and getting pneumonia could mean (best case scenario) 24 hours of care for 10-14 days. It could also mean that they have infected other people before getting sick themselves. It could also mean that a doctor or nurse gets sick after treating them, meaning even more strain on the hospital that is now caring for them 24 hours a day.
Worst case scenario, they die gasping for air, alone, in pain, confused, scared because the doctor decided to give the last remaining ventilator to a 18 year old woman who contracted the disease on her one visit out a week to a supermarket to get food for her parents and who has a better chance of survival.
Surely you can see the possible chains of events that their need for a drive and a walk could set off? Which part of it don't you get?