If I were you, I'd tell your father to get over it. If he saw what "store-bought" meat goes through before getting wrapped in plastic and put on the shelf, he'd never eat another steak. The chances for getting something contaminated are far greater when someone else does the butchering. And, what the other responses say are true about things done in batches.
If you have to use a processor, use a guy than bones the meat rather than cutting with a saw. All those bone chips scattered through the meat give it a bad taste, and boned meat keeps longer in the freezer..