The way I understand it is the bacteria itself isn't anaerobic (or rather, oxygen isn't toxic to it but it doesn't need it) but the toxin reacts with oxygen. Canned foods lack 02, so a contamination means the toxin builds up over time instead of breaking down quickly, which is how it is so widespread without constantly killing people. That's where the idea that aerating it could reduce the amount of toxin (if it was the toxin rather than the spores that was an issue).
Though I'm still confused about why honey in particular is considered dangerous for babies and immune compromised when they (the babies) are constantly sticking random objects in their mouths that likely have the bacteria and spores on them.
