Something equally odd happened with fyrstikken and voting with 0% power for me and another user, and I think it was in an effort to antagonize me as he would vote for the other person that was clearly butting heads with me, and that person admitted he was trolling, but before that was attacking and disregarding any kind of decorum
Im pretty sure that 0% thing shows on steemDB when someone upvotes or downvotes something, then removes their vote later. I have reproduced the effecct for you on the above comment so you can see it. This came from upvoting the comment above, the removing the upvote.
The 0% being an upvote and then unvote makes sense, since his bot votes for every single post here. He might go over that list later in the day and unvote those people that he dislikes.