Here's a couple you can use according to the person:
--It's safer to ride on the road than to walk across intersections or across the street.
--It's much safer than riding a scooter or motorcycle.
--It's even safer than driving a pickup truck, even a monster pick up truck.
--It's safer than riding on multipurpose pathways
--It's so much safer than not exercising 3 times a week and going for bypass surgery

Have fun, and don't sweat it. Goal is not to convince. Goal is to plant seeds of doubt. The fact that the person is raising the question, means they are intrigued. Some of these will eventually grow to embrace cycling. They are not really raising objections. They are looking for reasons they can give to venture out of safe space and try cycling again.