It's not 20% voting, they're offering delegators a 20x vote.
So if you delegate 10k hp, you'd get an upvote worth 200k hp. That's effectively self-voting 20x, and just cause you're whitelisted it doesn't make autovoting your content okay as we all know and has been proven time after time authors quickly tend to abuse autovotes with less and less quality posts and more farmy content instead.
Where the hell have they been? 😃 with that 20× upvotes I don't remember it coming my way 😃.
On a serious note though, it sounds unfair and thus I have undelegated, I'm sure having my 100 HP back will give me a more curation rewards.
It most likely will after curation changes after the hardfork since you won't be giving a cut to the owner of that scheme, which I'm sure he gets in one way or another.