The sense that I got from the thread is that disguise meta is such a persistent issue that staff has given up trying to police it.
Given that staff has given up on trying to police it, I believe that in the rare instances where it does come to staff attention, there should be severe consequences.
The 'solution' has been to expand 'disguise' and 'appear' functionality to allow players to radically change their characters' appearance so as to make it extremely difficult to tie two different presentations of the same character to each other. And the 'balance' to that has been to allow anyone to attack any disguised character for any reason without justification. Finally, the balance to THAT balance is the slight chance that a meta-gaming player might attack someone more powerful than they intended and because of that suffer unintended consequences.
The most obvious "problem" with that system is that the more powerful a character becomes, the less likely that they are to suffer the consequences of mistakenly attacking someone more powerful than they are.
If we take the contributors to the previous thread at their word, there is a small portion of the player base who are extremely good at metagaming and making it look accidental / unintentional / blurred "Oh, I THOUGHT that was okay. I'm sorry."
Given that dynamic, I suggest that the game needs a sliding scale of consequences for characters who staff catch gaming the system.
The scale should have two elements.
1. the length that the PLAYER (not character) has been playing.
2. the leniency afforded to the PLAYER for metagaming
As 1 increases 2 decreases exponentially, to the point where a long term player gets zero leniency and loses their character if staff becomes aware of them metagaming.
It seems to me that unless people face a serious risk of losing what they are cheating for (their character), some people will always continue to skirt the edges of the system and rely on staff leniency and understanding.
I can't speak for the newbie who got metagamed on, but it seems to me that a system like this one I am proposing would go a long way to ensuring both new and long term players alike that there are serious consequences for skirting the rules.
What do you all think?