You can easily tell a newbie that he's beneath you, or that the dark gods admire strength, not weakness, and so you intend to let him grow stronger before testing him again... etc.

Or you can pad your pk ratio and multikill.

This is pretty much analogous to beating some kid up, then doing it again and again afterwards because he called you an asshole for doing it the first time.

If someone is standing in Galadon asking where the trainer is...

... do you really think your role forces you to kill him?

No. You make the choice to be an asshole in real life.