I didn't read one thing in the story that made me believe the father was scared. Pi$$ed off, yes.
The father has a loaded .32 Beretta. His son has a shotgun. They had 20 minutes before the teens arrived to decide what to do. They chose confrontation.
They did not call 911, but instead chose to go outside. There were five teens, but the teens were unarmed. White pointed his gun 3" from the teens face with a round in the chamber, hammer cocked, and his finger on the trigger.
According to witnesses, the teen slapped the gun away from his face, White re-centered the gun and then pulled the trigger. That's first degree murder.
The jury or the prosecutor didn't think so. Story doesn't say what the original charges were so we can't tell if it was the prosecutor or the jury which found him guilty of manslaughter, which is at least a couple of degrees below first degree murder, depending on the state.