There might be a problem with punishing people with a low following with low curation rewards. Some people may be good at spotting quality content early on, or at least before all votes are made on it, but not good in publishing their own, thus probably have very few (or no) followers.
I think there should be additional matrics increasing one's UA, like upvotes on comments and replies, essentially motivating people to write something insightful, or to start a meaningful discussion (although there's a question how easily abuse of the reply mechanism is combatible, if the OP can delete comments, then spam replies won't be an issue, and if the OP practices in it, should others downvote???).
Upvotes on posts obviously matter, because we sometimes like someone's individual post, but their other posts aren't relevant so we don't follow them. Or we actually want a very customizable feed, and a good post deserves an upvote, but we don't want it in our feed.
And as @vimukthi said, reply and comment length are an important factor. If combined with the upvote count (multiplied by UA of the upvoter) it could allow those that aren't good with publishing their own content, but are active in discussions, to accumulate their UA, and not fall behind.
Edit: Also, succesfully curating popular content early own should increase UA, in my opinion.