I wasn't there, so I don't know what exactly happened at the home, but no, stalking is not legal, as she doesn't know what the guy's intent is when he pulls up to her house. Especially when he's packing. Nobody does, which could be argued created the lethal confrontation.
Like I said, it's an interesting case. I'm not saying the guy is guilty of anything, but there is a WIDE opening for the prosecution to argue that he dragged the confrontation out and created the scenario, when he had every opportunity to call the police.