The real cognitive load on minnows who would consider downvoting a whale self-vote or bidbot vote is retaliation. Since one whale can counter thousands of minnow votes, and very few cases of so many votes exist, it's extremely unlikely that minnows would brave retaliation even if it didn't cost them VP to do so.

The only reason I get rewards today is because downvotes cost Bernie. If he got them for free, I'd get no rewards at all.

This is a bad idea, and it will make things much worse.