That's really the point, he wanted to be a successful PK not well known pvper. Hell the only time he killed me is when I had a tamer afk at Jhelom, and I never saw him just the after math.
I had to explained PKing to my friend who is new to UOR mechanics a few months ago because he couldn't understand why someone would kill him, but then want to res him. i said something along these lines: "You know how you like to kill monsters to make money? You kill the easiest monster with the highest return based on your skills right? PKs like to kill other players for money and resources. So they go after the guys farming monsters because that is gonna be the best return for their time investment."
Eh, I just enjoy killing. Straight up. If I'm on my pk I'll attack anyone I run into simply for the thrill of the fight/hunt. I rez and usually don't loot so as to not discourage players.