I think most people who are not fans of ball pythons or snakes in general have a problem with snake owners feeding live mammals to the snakes. At least most people agree that certain mammals should not be part of a pet snake's diet. Not too many people get upset about mice and rats, but when you start feeding a snake gerbils and hamsters you're pushing the envelop.
The daughter of one of my friend's found some stray kittens in the family's barn and she advertised for homes for them online. One guy said he would take them all if it was okay to feed them to his pet snake. Definitely over the line.