Im cant promise that I will follow the advice, but it would be handy to know what you guys think about the punishment-level in the game.
As an NA admin, these are my thoughts:
First of all, the entire scenario is situational. If it's a guy I've never seen before, I may give him a written, verbal warning in admin chat. On the other hand, if it's a guy who has done this several times in the past, and been given warnings/bans, who knows the rules, I may go straight to a 24 hour ban.
Also, if I didn't personally see the attack take place, along with anything leading up to said attack, I'm less likely to use a ban or kick. If a player complains that someone intentionally TKed them, and I did not see it happen, I pretty much universally issue written warnings in admin chat. That is usually enough to diffuse the issue, and everyone moves on with their day.
However, being the sadist that I am, if I issue a written warning for a rules violation in admin chat and someone proceeds to troll/abuse the admin, I reserve and occasionally exercise the right to kick/ban them for being a pain in my ass. I consider arguing with me while I'm attempting to enforce the rules to be the game equivalent of "obstruction of justice".