This is an amazing work @Emrebeyler and the entire @dpoll team. These restrictions is a good way to sanitize the blockchain to really bring out the value it stands for. It is quite sad how people would always be on readiness to abuse others' intellectual capacity.
My suggestion:
I would advise that you also help the dpoll creator to limit voters by the level of acitvity of the accounts. SOme idle accounts may just be created for such purposes. This implies that an account that has not been active for a few days past should not just become active for the purpose of voting. ANy account that should participate must be active at least in the last 7 days before being eligible. The reputation, age, no. of posts can still be abused, but the level of account activity would rarely be.
Goodluck!
Meanwhile, thanks to @Theycallmedan for really spicing the value of @dpoll