Answer:
Emerson and Calhoun saw the Mexican War as a forbidden fruit because for them it would poison the United States.
Explanation:
To understand the answer we need to analyze their perspective. First of all, the United States has always desired to conquer Mexico, however, it was unconstitutional and it might lead them to face death as a penalty. However, the factor that made them call the Mexican War as a "Forbidden Fruit" was because they believed it was going to trigger smaller inner wars that would destroy the United States structure from the inside.
