Here is my issue with that. You put the power in the hand of the person who is... most likely, already being careless or, in some cases, malicious.
I'd rather offer a "Forgive" option, as Macc suggested and I mentioned earlier as well. You have the power to forgive, but not punish. 3 unforgiven TKs is a kick no matter what.
Here is how I see the Vote to Kick being abused. Player A is you, just trying to play the objective and enjoy the game. Player B is a troll, or someone who just takes offense to you or can't get over being TK'd the first time by you, which was purely accidental. Player B then continually seeks out Player A, gets TK'd 2 times more and now has the power to kick that player.
Sure, any system can be abused, but I'd rather not see punishment power put in the hands of players on any level, rather see the ability to forgive.