I don't see the problem with it ethically, people keep rats and mice as pets so what is the difference. I would however be a bit concerned about disease and parasites as previously mentioned.
I would have a problem with people stealing the little kids from next doors pet, or being cruel to the cat before killing it.
If people can breed rats, guinea pigs etc etc as food why shouldn't someone breed cats for the same purpose? I understand it may not be everybodies cup of tea, but I am not seeing any reason why not.
Having said that, personally I am to lazy and would rather just go to the reptile shop 5 minutes up the road and buy my snake food already killed and frozen, but then I only have one MD and possibly another in the next few days so its not like I have to keep up a constant supply of food.