I can't see why. Is not much different that seen a photo of an astronaut in a space ship. Winter in Canada is harsh. Outside there is dark and chilling, not much food or water and everything outside would kill this animals in one hour or two. Less than 24 hours for sure.

Is totally, 120% reasonable, to keep the animals inside at this time. Inside there is light, warm, safety from predators, food, water, healthcare and other chicken to fight, annoy, cluck or chat with, that is very nice when you are a gregarious species as chicken are.

And at the end of their life they will be insta-killed

But lets don't allow reality to ruin a juicy horror tale. Free Willys, so they can die frozen, or crushed to death by predators.