Might be a good time for them to sign. If they don't want to do that they could declare a state of war and demand non-military cooperation from NATO signatories. And the "law of the sea" is much older than the recent treaties, anyway. They could always act in accordance with the latest treaty and ask why they should sign if other signatories won't act on their obligations.

As the Dutch said while fighting the Spanish: "It is not necessary to have hope in order to persevere."