Just a thought..

[morshu9001]

You lose a kill if you get a TK, plus it's humiliating. That's reason enough not to do it. It would be even better if you lost something from damaging teammates, not just killing.

If the map is set up to make camping a good strategy, it's a bad map. Players are compelled to play optimally.

I don't agree with you completely on either point.

The damage thing yes. But a lot of people just team-kill because they think it's funny, or fancy themselves trolls. On a deeper level, if they are a newer player, or just not good at playing, it's an insecurity thing. They know they are not as good as you are and it makes them envious, and their only retaliation is to "troll". This is why I make the suggestion. Like i said, it's not a perfect idea, but it makes a little more sense imo.

And I have to disagree with you both on the camping thing, Sorry vector.
Camping is sometimes a very useful tool in a team's arsenal, in certain cases. Not the "Praying Mantis" thing, just squatting the whole round and waiting for someone to come by, that's just strange and makes me wonder what kind of people even do things like that. Psychopath suicide bomber types I would assume idk.
But it's useful when it's used to defend the flag-holder. Also in scenarios when you know someone will momentarily be passing by you, based on simple logical tactic camping is a viable part of the game. Some people just do it all the time in weird remote spots on the map. Which makes no sense to me, but hey, at least that little area is covered, right? And if you know they are there that can actually prove useful sometimes. Like if you have the flag and someone is pursuing, you can lead them to where you know your camper is usually at, and they can help.
Also if you're a sniper camping is loosely defined, because that's what a sniper is realistically supposed to be about. Planting themselves in a few key areas to back up their team when they go into the enemy base with automatics to get the flag. If I go into the enemy base and grab the flag, I HOPE a sniper is camping somewhere nearby when I come running out of there.

On the TK thing, I'd rather ignore the problem of trolls and worry more about the game balance among legitimate players. AC uses the same logic with flagkills. In my experience, there are very few trolls, they get banned quickly, and they probably don't care too much about giving people deaths. More like they think it's funny to headshoot a camping teammate and see gibs fly everywhere.

On the camping thing, what is your complaint about camping? Is it cheap? Like you said, it makes sense to do it sometimes, and it's part of the game. Poorly designed maps will make camping an overpowered strategy, meaning everyone camps, and the game is boring. On a good CTF map, it only makes sense to have one or two campers and have everyone else rush. I only see an inherent non-map-related problem with camping if it's OSOK, and everyone is waiting 10 minutes for a camping standoff to end.