I don't think the Catholic Filipinos were ever friends of the Moros.
Fair enough, and I think the divide is still playing out, but the point is that it is a lever to be pulled to break apart Philippine society and I doubt that Catholic Filipinos are fully in love with how the USA treated their nation post-SAW. The grist is there to lure them from the Americans, after all, Cuba did not stay on team USA and we see plenty of rhetoric today from the Philippines that is not pro-USA.