Can someone be silenced for something they say in private chat between two players? Such as if a player sends it to ATA?
Only if it is a threat to said players life and in which case laws will take presidence. Past that, no, PM and clan chat chatter can not get silenced - If you admit to cheating though, you can be banned. Past that, it is the other players choice to block and unfollow you and a clans choice to clan mute and or kick you. Cheers.