Just making sure, getting proof of someone obviously intentional TAing someone else warrens a ban.
A really short one in this case.
If you hit me with proof that the guy is intentionally bumping team mates, he will also be removed.
This is in no way better than TKing someone because he accidental TKed you the round before during combat.
Contact admins, either using the player to admin chat (i key ingame) or IRC (linked in my signature) before you break rules yourself because you are raging.