Hi dude, I'm the guy who was dealing with your case in-game. As you remember, you shot someone which I checked logs for, who was a fellow CT. I teleported to you to talk with you, only to see you shooting in the directon of a bunch CTs. I warned you for ARDM after I had a little talk with you, which you were fine with. From what you told me, you got arrested shortly after. This is because you can be punished both IC and OOC for your actions. When I responded to your request you left because you didn't want to do the time in the brig.
Now the reason you were banned is because you LTARP'ed, (Left to Avoid Roleplay) which you would've been put in the brig in this case.
Hope that clears things up.