Donohoe didn't care about his child in the car, in fact quite the opposite. He set up a nice little show that his little girl will remember for the rest of her life
The only reason the child is mentioned is to get some sympathy (it worked here ^^^) and thus leniency
What people are missing here too is that during the final confrontation, Donohoe starting beating Bates' car with his hurley. Bates didn't want to get out of his car and when he eventually did, he was non-confrontational and held his hands up in air. Donohoe then proceeded to repeatedly kick him in the head with his hurley
From a natural justice point of view, this was clearly murder. Obviously too hard to prove and Donohoe was keen enough to admit manslaughter
I feel sorry for the little girl. Chances are she'll grow up to be a piece of scum just like daddy-o