Doesn't quite work that way in the Philippines. The immigration has been the other way since the mid-late 19th century, when Spain finally managed to dominate the Philippine Muslims and open Mindanao to Christian settlement.
Mindanao was a large, underdeveloped primitive island with plenty of free land, as the Muslim tradition was to work their land inefficiently with slave labor, for which they raided the rest of the Philippines. When Spain put a stop to this slave-raiding, the land was fallow.
Millions of Christian Filipinos have been settling Mindanao provinces ever since, until even Mindanao is 80% Christian. Even now they are still buying land and developing agriculture in traditionally under-populated Muslim core regions like South Cotabato, the location of this incident.
The reason the Muslims revolted in the 70's was this Christian immigration.
It always works that way with muslims, especially in the Philippines. The Philippines were a pagan indigenous people who saw islam arrive on their islands and establish themselves. Islam was introduced in the southern Philippines in the 12th century, and by the 1400's on Mindanao. By the 16th century the islamists had established several large principalities, including one near Manila. In other words, islam was swallowing up the Philippines through procreation and establishing sharia law. There were no organized, capable armies there to oppose them. It was indeed Spain who came to the rescue of the Philippines before they were totally consumed by islam.
One of the great lessons of what you posted is that islam tends towards stagnancy and poverty because of its oppressive sharia law and barbaric mentality. Once the Spaniards arrived the Philippines began to prosper. Around 1570 the Spanish defeated the muslim ruler Soliman. Even though southern Mindaneo has resisted Christianity for hundreds of years, all of the Philippines would now be islamofacists instead of free-living Christians if not for the Spaniards and their Catholic evangelists.