No that is not a valid change. isReadOnlyTxLock is redundant.
If the lock really is "read only" there will be no transaction synchronization.
If there is a transaction synchronization, it will be because it has been upgraded to a write lock and the synchronization will release the lock at the end of the transaction.
So it means that if the transaction was upgraded to write due to writing some object then the next used read-only methods will be locked?