The concept "Rule of Law" has implications. Let's examine them:

Were the people Duterte killed convicted by, and sentenced to death by his country's judiciary? No. Were the people Duterte killed enemy combatants in a war sanctioned by his country's legislature? No. Were the people Duterte killed an immediate personal threat to him? No.

People can make all sorts of excuses based on personal (i.e. anti-"Western") ideologies, but these do not hold up to even the most cursory legal or rational analysis.

Duterte is a mass murderer because he has killed people without explicit judicial or legislative warrant, or immediate personal danger. He hasn't violated so-called "Western" values, he's broken his own country's laws. Mass approval of his actions is as irrelevant as mass approval of lynchings in the USA.

Excusing Duterte excuses Bush and Cheney.