The training is with Clark Aviation and all self-funded by the pilot (31k USD). So the airline dosen't spend a penny and Clark Aviation make money out of the regular supply of FOs.
My understanding is that, Airphil are desperately short of FOs and are 'not really' hiring expats (they are hiring a few with considerable experience on Type in a similar way to Cebu). They cannot get enough experienced local pilots to fill their needs (they have multiple aircraft on order), so are having to resort to cadets.