I sure hope that one odd buyer cant affect things so dramatically. We dont even know the mental state of the client and from what I remember this was a very strange interaction and had even told me privately that it was great.
I sure hope thats not the main reason because Fiverr needs to lookout more for its sellers in that case. It was the only 1 star review Ive had in over 4 years... very sad they are going in this direction