Principle: If a food product contains ingredients whose presence most consumers of that product would be upset to discover in it, then the food should be labeled as containing those ingredients.
Principle
most consumers would ingredient X be mad to discover → should be labeled ingredient X in a food on that food
Conclusion
Crackly Crisps don't need to be labeled for having genetically engineered ingredients.
Evidence
Most consumers would not be mad if they discovered genetically engineered ingredients in Crackly Crisps.
Evaluation
The principle said if most would be mad, do need to label. The argument said, for Crackly Crisps most wouldn't be mad, so don't need to label.
That's an illegal opposite (negation) of the rule, also known as the famous flaw Necessary vs. Sufficient.
Conversationally, the principle gave us one possible reason why you might need to label an ingredient. We can't assume that this is the only possible reason why you might need to label an ingredient.
Goal
Find an answer saying the author confused a sufficient condition for needing to label with a necessary one, or an answer pointing out a different reason you might need to label genetically engineered ingredients.