Actually, Buddhism did reach the Philippines. There are archaeological remnants, but there is also a Buddhist minority population in the modern Philippines, and it should be noted that Buddhism had an influence on Philippine religion generally (that is, the belief systems of the Philippines are informed by the indigenous beliefs, Hinduism, Islam, Buddhism, and of course Christianity). Most of the Buddhist artifacts found in the Philippines date from around the 9th century. Buddhism became an influence due to the trade relationships that Filipino datus/rajahs/lakans had with Buddhist polities. As the leaders began depending on foreign trade as a large part of their political positioning, they began devising ways to attract foreigners and gain an exclusive kind of relationship/diplomacy. This included adopting religious iconography and philosophies and integrating them into their own native beliefs. Buddhism was used in this way, but so was Hinduism and Islam. We can even see that from how the leaders styled themselves.

I realize this isn't a very long answer, but it's really just a case of a mistaken assumption. Buddhism did reach the Philippines, was adopted by Filipino rulers, and it still exists in the Philippines today, both through a minority of worshippers and iconography and philosophy (through storytelling largely) spread throughout Filipino culture.

Source for the way Buddhism was adopted and used: I cited this just the other day, but it's such a comprehensive look at the politics of precolonial Philippines that you can't help but cite it over and over - Raiding, Trading, and Feasting: The Political Economy of Philippine Chiefdoms by Laura Lee Junker.