I have no idea. Either way the reasonable thing to do would have been to wait inside until the guy enters before you shoot, I'm just saying thinking it's a break in rather than a guy at the wrong address to pick up his brother at 10pm isn't irrational, his reaction was premature.
I'm trying to look at it from both guys' perspective to see what most likely happened, then decide what went wrong. Ralph doesn't know he's at the wrong house, and the old guy doesn't know the guy outside is at the wrong house, so if I was picking someone up at night and nobody answered, I'd probably try to look in the windows to see where everyone is or get someone's attention, and if I was an 85 year old living alone in a high crime city, I'd probably not answer the door at 10pm thinking maybe someone is picking up their brother at the wrong address.
The goof from each of them is maybe call or text someone to figure out why the house you're getting your brother at has all the lights off like nobody is home or awake, and the old guy obviously should have waited until the guy actually broke in before shooting.