I looked through some of the evidence, and you even admitted that the guide was ripped - you only claimed that it was Khal who ripped it, and that you were oblivious. Nonetheless, you decided to put your name on it; in doing so, you implicitly accepted responsibility for it.
Your involvement with Sigex was certainly part of the issue, but it wasn't the only reason you were banned. In case you forgot, Sigex was never actually keylogged by staff - it was just a trap to catch you leaking to him. As it has been over 2 years since the ban was issued, I have to assume that the staff at the time had the opportunity to make a more informed decision than anyone at present; their decision to ban you will not be reversed.