There are two reasons we ask about guns in the house:
Suicide Risk (people who are depressed who own guns are more likely to successfully completely suicide than depressed people who don't own guns. statistically speaking)
and
Child Safety and Well-being. From about ages 2 through adulthood, the leading cause of death is Accidents.
I bet that same questionnaire had Q's about seatbelts in cars, helmets on bikes, drugs out of reach, and smoking in the house.
Doc probably refused to take them on as patients because they refused to be honest about simple questions.
You learn pretty early on as a Doctor that people are fucking stupid. Really fucking stupid.
You'd be amazed at the things people just don't seem to know. We have to ask some questions like this.