Maute-Abu Sayyaf-ISIS wants to create an Islamic Caliphate in Mindanao and the Emir of the Islamic State will be Abu-Sayyaf's Isnilon Hapilon.
Their goal is to create another "state or country" and by pronouncements, it is so obvious that they want to secede from the Philippines.
But as far Senator Riza Hontiveros is concerned, what the Maute is doing is not rebellion. She said, that for a rebellion to happen, a local gov't, like the Marawi City gov't the will have to declare its desires to break away from the current government.
It means that even if the whole of Mindanao has been taken over by Maute/ISIS, but as long as no "Local Government Unit" declares that are rebelling, then are far as Hontiveros is concerned, there is NO REBELLION.