Unfortunately I don’t think disabling the plugin will make any difference. The problematic data is already stored in the database, so it’s there to stay. I think we can safely add Symbol to the list of allowed classes. I’ll do that 
Edit: to be clear, this isn’t really the plugin’s fault. Previously, any data type was allowed to be stored in the PostRevision. The Rails security issue means we’ve had to suddenly change the behaviour and limit the allowed data types.