I think you did the right thing. A little strange how he was baffled by your behavior, given that you gave him fair warning that he was crossing you.
I'm pretty new so maybe I just haven't been around long enough, but I have found that in the majority of situations (even if there is nothing to skirmish over), I get shot on sight. Not always, in fact this one time I met a person that wanted the same fiber plant that I did and there was only 1 plant and 2 of us. We spotted each other and both tried to flee but then we stopped and said hi and became friends and traded goods.
I haven't killed anyone but I can't say I haven't tried to defend myself before.