Yes. It is cruel, especially as there are alternatives. Slugs get a light shock if they cross copper, so you could put a copper strip on the ground near your door and they wouldn't cross it. Rough terrain is also a deterrent, so putting gravel in the area near your door might help. And if he wants to feed them, make him feed them in one area, or ignore it. He might be just trying to rile you. It would be different if they were eating your rare hostas, but with him putting out bait, it's cruel to punishing their instincts. You might also try adding a bird feeder to attract more birds to eat them, (circle of life). And eliminating damp shady areas to make the area less attactive.