My cousin and her husband had three girls. Early on they bought into this nonsense and bought their girls dolls and Tonka Trucks.
The trucks sat in the corner, completely ignored and the dolls got played with constantly.
I also knew a guy who was a missionary in a Soviet Union country. They raised their kids with no toy guns. At the age of about four, their boy picked up a stick and shouted “bang.” They gave up.
That last line is delightful on many levels. It speaks to the open-mindedness of your buddy and his wife, as well as to our inclination to surrender to the will of our children and, yes, to the ones with the guns. I will remember your post.