Wonderful idea. You definitely get a feel for the bird hanging in midair from this. I think viewers must have been looking for an explicit horizon in the image. You didn't hit them over the head with the topic. LOL
The feeder really dominates the picture, both in size and brightness. I think it needs a major crop on the left to stop that beautiful long-tailed tit being dwarfed by it.
I think there is debate going on in voter's minds as it seems that the definition of horizon that most are going for is literal. However, I really love the interpretation of it that you've taken on it in this photo! Nice job!