Anyone can transfer Steem Dollars to @null and include the @author/permlink they would like to promote in the memo. The Steem Dollars will be added to the total received by the post and increase its ranking in the promoted content ordering.

I don't get this, if @null assets are frozen and removed later from ecosystem, how can they be added to "total received by the post". If this is only earnings displaying tricks (you see 10$, 9$ earned + 1 $boosted, but you earned 9$ only?), it will confuse many users and make them feel scammed I think.