Well, I'm a city girl and not an expert by any means, BUT there is a big difference between maggots and grubs. What most composters are feeding are probably grubs of some sort - not actual "maggots".
My granny used to raise grubs ... they don't gross me out. But maggots - that's a different story. If you've ever seen a pet with fly-strike, you might also cringe at the sight of maggots.
I know a wee bit about botulism as a parent. A bacteria actually causes botulism - and it's often found in in dirt and dust, which can contaminate honey. Honey can cause botulism in a baby because their immature digestive system can not process the spores that cause it. (By one year old, it's generally safe.) If the bacteria hangs around in the body too long, it germinates, multiplies and produces a toxin, which causes the illness.
I bet the chickens that are "immune" to botulism have better digestive systems.
--janis