How this can be done - I don't know, but this should be the goal.
Pretty sure allowing authors to chose how much percentage they want to give to curator would solve this.
People like me delegate to bot because its more profitable than curating, as I explained in this post https://steemit.com/steem/@snowflake/enter-a-whale-s-mind. The vote buying popularity came as a result of reducing curation rewards from 50 to 25%. So making curation more profitable would encourage manual curation. I know that if I could earn as much as with a bot by upvoting content that I like I definetely would do this.
Flagging the bid-bot posts should work just as well.
If whales are soley motivated by money, and the bid-bot posts they've lent their steempower to, stop earning as well, they'll find another way to use their steempower (perhaps curatgion guilds).
It feels like operation-cleanup is aimed at writers on the front page, but it is really aimed at the delegators who support the bid-bots with their steempower.
I was offered 5,000 Steem to delegate 100,000 SP recently. I'm sure that's not sustainable, but even at the going rates I'm afraid the curator will need to get 80% share or something ridiculous.
That said, I'd support a 50%-50% split. But we need something more than that.
Congratulations on getting in the top 50 witnesses.