Why does START TRANSACTION WITH CONSISTENT SNAPSHOT not work with SERIALIZABLE isolation level?
The WITH CONSISTENT SNAPSHOT modifier starts a consistent read for
  storage engines that are capable of it.
  
  consistent read A read operation that uses snapshot information to
  present query results based on a point in time, regardless of changes
  performed by other transactions running at the same time.


With SERIALIZABLE isolation level you don't need to use a snapshot because all necessary data is already locked by your transaction.  

SERIALIZABLE isolation level should be more ACID compliant than REPEATABLE READ because the second one allows non-locking reads which may lead to a violation of the I (Isolation) rule of ACID.