No matter which way you put this, if there's a one betrayal boot, that isn't fair, if there's a 2 betrayal boot, that in some cases can't be fair as well.
For example, you throw a sticky grenade but your teammate jumps in front of you, he dies, you get booted for an accident, or someone who doesn't like the fact you get a power weapon, such as the rocket launcher, they want to get you booted, so they jump in front of you getting you booted for their idiocy.
Two betrayal booting could work the same way, you could shoot a rocket, or throw a grenade and two teammates get in the way, you get booted for an accident.
You could be driving a warthog, turn a corner and someone not looking runs in front of you, you get booted.
There are too many flaws to betrayal systems for any one system to work, especially since the last few times I played team games, I get betrayed for taking a weapon, or because I accidentally shoot someone and they think I'm trying to get them killed.
Betrayal booting doesn't work for the simple fact that accidents do happen, and even if it is an accident, people today seem to love to kick people anyways, I don't know if it's because they are just arseholes, or because they are in a bad mood, but people DO kick others for things they know to be accidents.
Also... I don't know why people keep making these threads, there's so many of them, why not go voice your opinion in an existing thread instead of making a new one?