If Browns WR Mohamed Massaquoi caught this pass, would Jerome Harrison have still been fined by the NFL?

Of course. The NFL would say that he was a "defenseless" player. Harrison is known for laying big hits, and being fined as a result. Most of the fines if not all have come when the player had the ball. Or the QB was caught on a late hit. That particular play looks like it does hurt, and I think the NFL would have fined him for it had he caught the ball.