Whether a bull runs with the cows or not, the meat changes after about 15 months of age. By that age, he is ejaculating, with or without a cow. Not saying the meat would be bad, just different. The fibers change (stringy??) not sure of the technical info. Toughness will be the problem at 2+ age.
Why not finish off the 1 year old. He should be around 1000# and ready for grain finishing.