- Moving from the US sphere of influence to the China/Russia sphere - The US historically cared little who they were supporting (e.g., Marcos,) as long as he or she was anti-communist, and still retains many unsavory allies around the world. China and Russia, however, coddle the likes of North Korea and Syria that literally enslave and bomb their own citizens. These guys really don't care what those governments do to their own people, so if you were planning to be a brutal dictator, you'd shift towards the East, too.
- Co-opting the police - Extra-judicial killings can be investigated and prosecuted by a new president, so allowing police to commit these crimes also binds them to the current president. Well-paid and powerful on the one hand, risk of prosecution on the other, which would you choose?
- Creating an atmosphere of uncertainty for foreign investors - Once the foreign businesses pull out, foreign governments will care a lot less what goes on in the Philippines. There'll be some noises made in the UN, but that's all. If it gets too serious, then you ask Russia or China for a veto.
- Inflaming nationalism - Other than religion, the tried and true way of justifying harsh action against criticism. Who wants to stick up for drug dealers or American imperialists?
Now, I'm not saying this is the plan, just that it sure looks like one when taken altogether.
Almost immediately after taking power, Duterte insisted on burying Marcos in the heroes' cemetery. This isn't a grand political gesture to unify the country, as it might've been if offered by the Aquino family, so it must be a payment of political debt. The debt was either so enormous, or he cared so little about what it would symbolize to the victims of Marcos, that this couldn't be shelved.
So I think the puppet masters will emerge from the shadows soon. I hope the Filipino people are alert and brave enough to avert it.