The rules explicitly state that all bots must have "bot" in the name so that they Do not get paid for chatting. You make a bot that does not follow those rules, and illegitimately gain .5 BTC. I cant understand what the misunderstanding his here, you stole .5 BTC from Tradefortress by using a bot that was not allowed. You get paid for chatting on coinchat, not having a bot spam for you, and because of your bot, Tradefortress is out .5BTC hence the negative trust.
I'm really not understanding where the question of, why don't I get negative trust for stealing .5BTC from someone? If it was an honest mistake, you would have seen that it was against the rules, said oh sorry, and returned the ill gotten coins.
Edit* And after thinking it over, I don't really buy that you werent aware of the rules in the first place. Why would you have named your bot b0t rather than bot had you not known that names with bot don't get paid?
Salty sums this up well, I agree with him. OP looks to be completely in the wrong here, TF in the right.
in this particular case maybe....