Watched the ending of Jon and Kate Plus 8 with the rabbit... Two thoughts. First of, I would think that any rabbit a magician has would be used to this kind of "show", if you will. I'm sure the rabbit is used to being prodded and poked.
However, I do think that the parents and the magician should have told the kids to calm down a little and be gentle as they were being a bit rough with the rabbit. Maybe I'm blind but I didnt see any of the kids out right ATTACKING the rabbit, just petting and rubbing a bit roughly.
I'm no magician but my Kaylie is very good with children. She'll just sit there and let kids poke and prod her. She has also been in a noisy environment most of her life. We have a screaming parrot, two giant dogs that bark all the time, loud cars that drive by and other various sounds. Granted, this is in a home environment but she has been in it for a couple of years now and doesnt even flinch when the loudest sound goes off.
So I think it is very possible that the magician's rabbit would be used to loud sounds and being poked at. I just think the magician could have educated his young viewers a little and show them how to properly pet a rabbit.