@Valefor.Forgotten
I read your posts and I don't mean to dodge your questions. You bring up good points. If I made a mechanism to add a mule to an account with limited options such as no forum/pm/comment privs, I would want to do it after I resolve this hidden option first. I think alot of users don't even know what hidden means and some have their main characters set as hidden and they don't know it, which is understandable.
Now this limited feature would take some planning and work. Such as, what if someone wants to "unmule it". I can't just have an option to do it, because someone can toggle, make forum post, toggle back. There would have to be limitation like a timer.
If a user does't want others to know they have x,y,z character, unlink and make a new account with characters.