This is a great example of why in rule 10 account sharing is begrudgingly permitted but discouraged. But as far as I can tell rule 10 isn't being broken here unless you bought the characters which there's no reason to believe.

Let's look at the facts:
1) You told guy in screenshot that you wanted to stake,
2) he said you could use their character and placed 100k gp on it and then told you the password,
3) he did not give you permission to use any other characters,
4) you discovered the pw worked for the rest of his list and assumed control,
5) then you got banned because the player in question claimed they had been hacked.

Clearly, this is a simple misunderstanding and a great example of why we discourage account sharing, and how unintended consequences can arise from account sharing which are entirely your and the other players' responsibilities.

You have been unbanned with the condition that you return the items that you took from the characters that weren't istakenaked. You can give those items to the player himself or a mod who can transfer them for you. This is not optional due to rule 6 which concerns unauthorized transfers items and accounts. Note that the original creator of an account will always be able to recover their own account, regardless of if they give them away intentionally or accidentally, which is another reason to be suspicious of account sharing.

Again, it's totally understandable to see how you could have interpreted the other player as giving away his list; we'll call this a simple misunderstanding. Welcome back.