By my understanding, what would happen if the tongue never dropped was not specified, and what had been said left what would happen if the tongue never dropped up to interpretation -- which of course means that both parties read the interpretation as that which is most favorable for them.

This was an agreement for an exception to the otherwise agreed upon drop rights, so a gap in the agreement should be resolved by defaulting to the otherwise-agreed-upon-drop-rights.

In this case, the default distribution of items was "Your Orb, Your Drop" and therefore Linh is in the right in expecting to keep drops.