X3It's a huge stretch to go from cat sitting on coop to killing hen. Cats are attracted to chicken coops because there is feed in it. Where there is feed, there are mice and small birds.
Personally I have never had any issues with cats and full size chickens. Can a 10# cat take down a 5# hen without a fight, without making a ruckus? Could a cat drag off the body leaving no trace of feathers or the body? The largest thing my cats have caught are baby bunnies. They are interested in chicks and would kill them if given the chance. They avoid the chickens.
People's stray animals should not be on your property but something other than a cat walked off with the hen.