Anduck lies. :/
Read the PMs again. Notice where I type "ah, until this point'? That is when I lost trust for him. Around a week later, with no further communication from him, I changed my rating. If you choose a scammer's interpretation of those words over mine, then you will believe him over me.
I did read the PMs. But what I noticed was that you asked him to change his ratings first, otherwise you'd change it, and then only after Anduck said that it would be better if both of you remove the ratings, and only then did you found the rating to be retaliatory.
I am not saying anduck is a scammer but nor am I saying what he did is ethical. The rating was good on its own, the issue here is when you changed it, and it does honestly look like retaliation after reading those conversations.