There somes to be some kind of misunderstanding here.
There is no injustice.
You are wrong on two counts.
1.You killed an underlevel player without justification, which is against the rules.
2.You threatened another player, which is against the rules.
It's clear that this is you as a player threatening someone. Why else would you make the threat on another of your characters? Why else would you actually have reason to threaten another person? Do random people come up to you in the street and say "I'm going to kill you for reporting me to Buddah/God/Allah/Pan"?
Claiming it is part of the game is disingenuous at best.
Are we supposed to be grateful that you don't stalk people in real life?