Grocery shopping means you need to get out and expose yourself. While this is not 'dangerous' it does means you might get infected which in turn might mean you

Grocery shopping means you need to get out and expose yourself. While this is not 'dangerous' it does means you might get infected which in turn might mean you need to get medical care which in turn means you end up increasing the case load at a moment when the health care system is already straining or overloaded. Not having to go out shopping means you don't run that risk. That is where he gets this: basic common sense. Limit exposure, limit spread, flatten the infection curve to such a level that the peak 10-15% which will need hospitalisation does not exceed the available capacity.