Usually there is a way to appeal bans, if these forums have a way I don't know. Logically they should given you can appeal in-game bans, so I don't see why the forums should be any different.

Depending on the severity of the "offence" I do think some bans should be lifted especially if years have since passed. I'm sure a lot of people who got banned were stupid kids who said stupid crap and are by now adults who no longer act this way. Definitely if their subscription to the game has remained very active during the ban SE should entertain the idea of giving back their voices.

As for the perma ban of the player due to reporting their own thread after realising an error, that could have been an automated system that simply scanned for keywords as well as potential lodestone entries of characters. If a person did manually ban them then that certainly was a very stupid decision or it could be a simple case of not reading the report as a whole properly. I wonder if the player appealed the ban. It's not unusual for people to be unaware that you usually can appeal bans.