Ideally the stake should be bound within certain rulesets, e.g. release X amount for just what you suggest. But as of now the stake was ready to be fully powered down or to be used for controlling large part of the Steem blockchain.
1 Steem = 1 witness vote is all the rules necessary. However that will reduce the undue influence substantial stakeholders have wielded over governance heretofore, and effect equitable distribution of influence to all stakeholders, regardless of the size of their stakes.
Either contemplate legal action for this tort, or end the threat 30x multiplication of stake represents to decentralization.