A few things to keep in mind for a feature like this:
Too strict and people will be afraid to help their team mates. I would much rather people get stuck in and hit stuff, even if it means I take some team hits sometimes. I don't want people to play in a timid way when that could get me killed. I want them to make semi risky attacks if that means they are learning to be better players and could help me kill someone. You don't get better if you won't try the risky attacks like long spearing around team mates. People shouldn't be afraid to try this stuff. There's obviously somewhere you draw the line though
Another thing with a strict system is people will intentionally get in the way to get you kicked. It could seem innocent but the guy knows he's just running in to get people to hit him with hits that he knows probably won't kill him but gets someone kicked from the server
As it is now I think it functions as a way to limit intentional team hitters, but they have to hit a lot before they are kicked since you only seem to be able to report 1 team hit every so often. So in that sense it doesn't work that well, but works eventually. Careless players probably aren't really punished much. The damage from the team hit isn't always what kills you, its the interrupt that allows enemies to get a hit in. Maybe we could have a system that if you Ctrl-M someone if you take enemy damage say 5 secs after taking team hit then the guy gets +2 to his limit or something
TBH I wouldn't really change much, maybe lower the limit a little. I just don't want people to be afraid to attack, that will be far worse than taking a few team hits every so often. It would be bad for teamplay if people just want to leave people alone to fight