Unfortunately, I've already had to add one back for a user who immediately began harassing me after I removed a feedback rating for them threatening to physically harm me.
So you are getting harassed by the member you removed the rating from? He is angry that you changed your mind and decided not to tag him
When it comes to OgNasty, he's usually blatantly lying about such personal interactions and has a habit of sending harassing PMs to other users. What really happened here is that he came up with an excuse to move his red trust rating to the top of the list after the user whom he red- trusted previously had gained a few positive ratings from successful trades, which would indicate that there isn't high risk in trading with said person but OgNasty can't have that with users he dislikes.