Wouldn't exchanges have to cooperate to a high degree here? The coins in each user's accounts usually just correlate to a percentage of some total supply owned by the exchange. If I transfer 100 coins to an exchange right before a 50% freeze, I'll still be able to trade all 100 of my coins, even though the exchange's wallets will have the funds tied up. The problem will be when I try to withdraw, or rather, when more than 50% of their stored funds are withdrawn. It would benefit those who withdrew earlier, and it seems possible that this could avalanche into a bank-run type scenario. In order to avoid this issue, all exchanges would have to artificially implement the coin's logic within their trade mechanics. Thoughts?