Why not in Creed?

I understand them killing off Paulie but Rocky's son is the only one left in his life after the Rocky Balboa movie. Even if Marie and her son moved on its fine. Still you would think after Rocky Jr quit his job to be closer to his dad he would be somewhat relevant in this movie. Big mistake not bringing back this actor to put a final close on the Rocky chapter and transition into Creed. Seems like a lose end.