The bolded part show's admin stance against accounts sales in particular, we have to analyze in case by case level to avoid confusion and distractions from the main subject of arguments.
It was only made bold in the quote but the original unofficial forum rule has wasn't made bold. I think that rule gives the forum users the chance to take decisions on sold accounts and that's where the trust system comes in handy. A negative or neutral trust from a reputable member is a good as banning an account because anyone doing business with such account will only be putting themselves at high risk.