His reason for the ban is
http://news.abs-cbn.com/halalan2016/lifestyle/05/10/16/duterte-proposes-nationwide-liquor-ban-spokesmanI know that Duterte just won and this proposal may not even be implemented, but this is the kind of thinking why I did not vote for him, and maybe why a lot of people voted for him.
""The reason he has this liquor ban (in Davao) is because we have to work the next day, all the (restaurant) staff have to work, as well as the customers," he said."
So he thinks that without the ban, people will just drink until the wee hours of the morning, so they have to be protected from themselves. But then:
"High-end Davao hotels are exempt from the liquor ban, he said."
So actually, the ban on drinking only applies to poor people, if your rich, you can actually drink until the wee hours of the morning. It's not that Duterte thinks drinking is bad, it's only bad if you're poor.