Members of my family ran a grocery store and a butcher shop. The ground beef was made from the trimmings from the steaks and roasts with added lean meat from what we called boneless cow or bull........older beef that wouldn't make good steaks or roasts.. The boneless meat was often used a couple of days after it was chilled and boned....within 3 days of when it was killed. I ate that meat for many years. I have never heard of "dangerous enzymes" in properly refrigerated and correctly cooked fresh meat.
