Allowing ferrets to mix with other animals requires rational thought as to the likely hood of injury either pet. Large animals can injure a ferret and a ferret will kill a rabbit or similar pet.
I know of a case where several ferrets escaped from their cage at a pet shop whilst closed, killing the rabbits and guinea pigs plus wrecking the the shop displays. That was an extreme example; ferrets are intelligent, good natured creatures when cared for correctly and treated with respect.