The downvote will do you no harm at all as they have little HP. Downvotes only affect your reputation if that person has a higher rep score. I wouldn't worry about it. People are free to do what they want on Hive and this person is trying to make some sort of point. I get lots of tiny downvotes and they can only take a few cents off my posts. The freedom of Hive means they can be trolls if they want.
!BEER
Ah, thanks for clarifying that!
That's fine then! 👍