Not a bull but we ate Katy Jersey at 5 years old, and Flare Jersey x Red Devon at 4, both awesome beef. We had expected that it would all be braising rather than any roasting or quick-cook steaks but in fact the steaks were wonderful and so were the roasts. Just be really, really sure to let the meat relax for at least 30 minutes for a joint or at least 10 minutes for a steak after cooking before eating, or it can seem as though it's tough - but if properly relaxed it becomes melt-in-the-mouth tender.
Oh, and we also had burgers made from each, all delicious, real depth of flavour.
I would have no qualms about selling 5 year old Jersey cow meat, with the above guidance. I don't know if being a bull makes a difference, though.
It may or may not be relevant, but we sent our Shetland tup Chad off at 3 years old, only a few weeks after tupping, expecting the meat might be tainted and we'd feed it to the dogs, so had it all minced - but it was fantastic, made the best lasagnes ever.