To elaborate a bit, apparently Clostridium botulinum bacteria produce spores, which are very resistant and don't give much of a fuck about anything — e.g. boiling at 100°C. That's why preserved foods are boiled at pressure with higher temps, and pickled with acid and salt to kill the emerging bacteria. Toxin itself can theoretically be destroyed by prolonged boiling, but it's highly potent in very small quantities, so it's always recommended to just toss spoiled canned foods.
Bacteria themselves don't live in honey because of its high sugar content, but if it has spores, those would turn into bacteria in ones' intestines, and children's immune system is not equipped to deal with that.
