I think Bitshares is making a wise move in eventually including vote decay as a tool to weight active vs. non-active voters, gradually faze out votes from lost keys, etc.
However, I think the same type of gradual delay is required on the incoming side as well, in order to limit the possibility of rogue proxies or coordinated voting attacks.
I would propose consideration of vote vesting as one type of safety mechanism – to allow for community voter mobilization in the case that an extremely large vote is placed.
Maybe we could start with something like a 24 hour 0% vest period (but with network notification of incoming vote), followed by initiation and gradual vesting to complete within the next 24 or 48 hour period?