according to PDI, that happened because of consultative voting.
Almost all maguindanao residents are muslims & they are led by a certain sultan.
now this sultan, in substance, also acts as their spiritual leader, which in essence has the rightful opinion on what to be done. needless to say, they must follow his convictions because failure to do so will mean disobeying not only their sultan, but a heavenly order as well.
now GMA & co, knowing this kind of rulership in maguindanao, made ligaw to this sultan months before the election, and she eventually won his heart. kya this sultan pronounced that only team unity senators should be in their ballots.
that's how the 12-0 poll came out.