Bittrex was shut down as per our request. We will be issuing a press release tonight with details on the direction we will go to solve this solution and prevent it from happening again.
One way used by other coins to prevent similar issues is to have a test in the wallet that disconnect old versions that try to sync.
One with old version simply will not be able to connect with others and so they need to update the client.
Maybe with a fork in progress the code should had to test if wallet is old and block<227000 it is allowed, but if block>=22700 it will be disconnected from the network.