I agree voting on day 6 is abusing the pool. But people tend to try and take advantage, thats normal and downvoting with no warning will scary away many good investors. Without the mass the system wont thrive.
I think its more scalable to deduct the intreset from the voting rewards by days with additional penalty. Some behaviors can also trigger a waring automatically - don't vote your own comments etc. If the bot finds a bad pattern.
But turning on the downvote punshiment in my opinion should be still manual. We are in a fragile phase and we want adoption and communication.