Whelp, he just lost any claims to the Spratly Islands the Philippines ever had.
And any military assistance against the Moros insurgency.
Further, if he wants to up the game, the Philippines could be frozen out of the global financial network a la North Korea. Good luck maintaining the transport fleet needed to maintain travel to/from all their islands without the ability to wire money to the companies that make replacement parts for their boats.
Of course, China can step in and help. But then the Philippines becomes solely dependent on China for all facets of their existence, much like North Korea.
It's a dangerous game to play... for Filipinos and the Philippines in general.