This case is a good one.
Where there is no issue as to whether or not the defendant killed the victim (there is no issue in this case) and where the only issue is the defendant's state of mind (which in this case was whether or not the defendant had a callous disregard for human life) then cold silence in the face of a dying child or a screaming mother can be interpreted by a jury that the defendant really didn't give a damn about the consequences of his actions and had no regard for anyone other than himself.
I think the facts of this case bear out that the defendant didn't really give a damn about whether or not he killed a child. His only concern was for himself. Just as it was when he was driving drunk and speeding.
In all honestly, when someone does something like this, the last thing the parents want to hear is the idiot slobbering all over everyone expressing remorse.
IMO, just shutting up and remaining on the sidelines is about all you can do.
The guy is already the slime-ball to beat all slime-balls.