My chickens certainly get a portion of my compost bucket, the portion that the piggies don't get first. But, I'm very very very careful not to put pork or chicken in there. I don't have an issue with the chickens pecking the last bits of meat off a t-bone steak or the pigs getting some lamb riblets to gnaw on. But, I raise essentially all our own meat, and I know it's grass fed and never given antibiotics.
There are also some issues with cat/dog meat making it into the chain, where most were put down by vets and there are measurable ammounts of the drug was found in the 'meal' made from them.
The pig worker thing really freaked me out. They blast every bit of matter off a cracass using air and water, through a drain in the floor. Then, all the water is pressed out and you are left with "porcine meal". I mean, I don't want to see things go to waste, but to take that much effort to get spinal column tissue seems not quite right.