I think he is reveling in this. Loving every minute of this deranged madness.
He has no capacity to love, feel empathy or even experience what would be normal joy for the rest of us. I think that attempting to appear sorrowful actually brings him real psychic pain. Look at him every time he addresses the news of the latest slaughter. He's forced to look sad and say that this debauchery is wrong and has no place in this country. Does he LOOK authentic when he says that ? Of course not. I think it actually pains him to put that out there.
Secretly, he's delighted when this happens and scores of ("those" people) are murdered. Because it's being done IN HIS NAME. (Mostly) young, white, disaffected males are killing the people he hates, the people he rails against at his rallies, the people he refers to as "animals who hate America." Think about it. Knowing how he needs to be adored, worshipped. True fanatics are killing for HIM.
I'd be willing to say that he lives for this. He's been inciting violence since before he took office. And now sick, twisted, malleable young men are acting on his fantasies. He speaks, they listen then act and kill. FOR HIM, and him alone. It is like heroin to him.
This is his ultimate wet dream. And he loves every minute of this.