I have heard a similar argument against giving peanut allergic kids soy nut butter and other peanut butter substitutes. The argument goes that children with severe peanut allergies need to be taught to avoid brown sticky things.
There was an incident like that at my DS's preschool. The class was peanut free because of a little girl with severe allergies. The allergic child had a sibling who loved peanut butter. After her little sister was born she begged the mom to continue to allow her to eat it, so the mother decided that she would allow her to take peanut butter sandwiches to school, but not to eat it at home -- figuring that there wouldn't be as much risk that way. However, one day the girls came to school and somehow ended up switching lunches. DS's classmate who was 2 knew enough to bring the sandwich to the teacher and said "Can I eat this" and the teacher told her -- it must be soy nut butter, go ahead, and the poor child took a bite and immediately broke out into hives all over her body. She ended up OK, but I know it was terrifying for both the child and the teacher.