If you believe in "proof of brain", then when you downvote, you should use the minimal amount of SP possible. Otherwise, "proof of brain" is non-sense. 99% of the folks voted positively, meaning the "proof of brain" was revealing a favorable outcome to the post. Regardless of how you felt about it. When you use your full SP, your making POB irrelevant. You reduce it to "Proof of Steem Power"

So if your a true believer of POB, then stop using your full SP when down-voting and only use the smallest unit possible. Otherwise, your just a hypocrite.