Participating in a campaign that is legal in the forum is not a crime.
If with "not a crime" you mean it's allowed by forum rules, then indeed it's allowed on the forum. But scamming, and running a scam exchange, is
allowed too! Feedback is generally considered to be useful for things that aren't covered by forum rules, and promoting a scam makes it likely some people are going to call you out and tag you for that.
What's with the retaliation negative feedback?
This would be a great text for Neutral feedback, but it's trust abuse to make it negative. Please read my
Beginners guide to correct use of the Trust system.
The only person that can remove your negative feedback is the user who placed it. Retaliating doesn't help your case.
If you think someone's feedback is inaccurate, exclude them from
your Trust list.