More logical cause of SIDS is clostridium botulinus spores containing botulinus toxin in honey. Infants don’t have the enzyme in the intestine that deactivates the spore thus causing death due to botulism.
I am not sure botulism can be readily equated with SIDS. Infants usually exhibit symptoms like constipation, difficulty feeding, etc. I think it is interesting that half or nearly half of all cases of infant botulism are in California. Since in most cases, there is no honey in the infants history, it is a widely held belief that it is the spores in the soil.
I would think that the babies, at least some, would exhibit signs of illness in that case.