What matters is if TF used the trust system in accordance with its rules. According to theymos, Therefore, TF can use feedback for whatever he wants. If it becomes frivolous, then people will ignore TF's trust or the entire trust system. Action does not need to be taken by the trust system admins.

Since I tend to be very conservative when it comes to deciding if something is unethical, it sounds like TF gave someone .5 BTC because his banning mechanism and bot detection were inadequate, and now he's retaliating through the trust system. However, the OP was gaming the system (coinchat) and not following the rules, and other people would call that unethical. TF would go so far as to say that it's stealing! It's hard to determine if that makes someone trustworthy without a definition of trust that everyone agrees on.