I think you are assuming he knew something was wrong. If I’m coming and going and hear a baby cry, I’m not going to automatically assume 911 needs to be called. We don’t know that the baby was crying continuously. It doesn’t say he could hear him while in his apartment. I don’t blame him, but I imagine there will be people that do as modern society always wants to find someone to lay blame on.
I certainly agree with you, 100%. A crying baby almost always means just that, a crying baby, and nothing more. It would have taken an extraordinarily perceptive person to notice that something was wrong.
I hope that the man is not too hard on himself. He is in no way at fault.