To say there was 'No' or 'Bad' RP reason for killing is either being ignorant, or butthurt, respectively.
My character was actually offended, whether you knew you were insulting him or not. My character, as many can attest to, is a tired and proud dwarven lord - quick to action, very irksome, and impatient (though he tries to hide it most of the time). Being called a human is a huge insult to a dwarf - they consider them weak. Then you went on to dismiss him completely. Add that to the fact that my character has received nothing but violence against him before he came to this land, and you have the perfect storm. (TL

R He doesn't put up with bullshit like that.)
Especially considering your character simply respawned, killing in this RP might as well be the equivalent of my character punching your character in the face. No lesson would be learned if I simply hit you once - not only would you have most likely hit back (attempting to kill me in addition) instantaneously, but you would simply regain hearts and walk away otherwise.
Your character got what was coming to him for being ignorant and rude. That is all.