Aloha,
You can get chat banned for a couple of reasons.
1: You can get chat banned if enough players report you with "Misbehavior in Chat." This isn't always automatic.
2: If a staff member sees applicable data that warrants a chat ban they can take action.
There is a reason that those chat bans are across the board for all in-game chat avenues.
Anyone that is chat banned if they feel was unjustly punished can submit a customer service request to challenge it. And I have seen some chat bans get removed from a genuine error. That being said, MOST our bans are due to valid reasons, either a complete violation of our EULA or excessive reports from other players that were for valid reasons. Furthermore, chat can be shut off or if someone is being personally attacked or griefed in-game, replays can be submitted with a write up of what is going on and it WILL be handled.
TBH, however, most people that I have seen talk about unjust chat bans, etc, after reviewing chat logs and records... well, in my experience 99% of the bans are justified.
Mahalo,
-Hapa