Totally agree with harsh punishments for this kind of BS.
Just one thing: short warning in chat or question wtf he is doing.
Some TKs are intentional AND justified.
E.g. I have developed the habit to deal with those teamwounding idiots at spawn by turning around and killing them without further questions.
BTW we had that on another thread already, and I still like the suggestion that a general punishment (gold, exp, or both) should be in place for any teamwounding (intentional or not), and that it should be hitpoints-based, not kill-based. So people might actually watch their swings a bit more, and the intentional teamwounding would be covered as well, because these idiots usually do not kill you (to avoid being caught and punished and get the -1 killpoint), but severely wound you and other teammates.