you obviously don't know anything about the fermentation process. Body temperature doesn't kill yeast. it thrives as long as there is sugar. It dies when the sugar is gone. That's how yeast works.
Go back to college and take a microbiology course which usually has a section in fermentation. In fact, the stomach is exactly where sugar is fermented and it doesn't take days at that temperature. At room temperature it can take days, but the higher the temperature the faster it reacts. Obviously, there are many yeast strains out there and they all react differently. Some are fast acting and some are slow acting.
Instead of acting like a fool, educate yourself. don't put down Nancy's products. They have experts in the field that have worked on their culture and they know exactly what they are doing.