Pretty much what Goretooth said. Also, the whole argument of "intentional or not" no longer applies as they changed the text up for what people hit M for now. The system is there as more of a "hey watch your swings/shots" kind of thing. Civilian has been around for even longer than I have and he's never caused trouble to the best of my memory. You're also not the first one to call ATS a bunch of jerks, elitists,trolls,assholes and so on. It seems a bit out of character for him to start taking offense to it now and acting in such a way.
Also, given that you have two clan members vouching for you, it's still essentially a his word vs hers kind of thing. We took all of that into consideration when we were reviewing the logs and all of the other evidence.
I understand that you've never been in trouble at all either for as long as i've seen you play, but hitting a guy multiple times in under ten seconds and killing him with a head shot through archery is pretty hard to do in any circumstances, let alone when it's revenge against someone hitting M.
There is a decent amount of evidence for both arguments. One side simply has a more convincing case, and i'm not the only admin saying that. Several of us came to the same conclusion going by the evidence we had, including the one who issued the ban.