I don't know, they should have done it when Obama committed even worse Facebook privacy violations back in 2008/2012. I guess when you have Chris Hughes working for your campaign, it's easier to keep things under wraps and spin what does become public as a positive. It was only after Trump won that this kind of use of the data became an issue for the press. The Obama-era articles on this subject actually celebrated the use of these techniques almost universally.

And what policy is in place now that makes sure that these 3rd party Devs won't sell whatever info they do collect as per post-2014 policy?

You're not understanding what he said. The Facebook platform was completely neutered in 2014. They broke my (and most other developers') apps by disabling access to almost any friend information, even things as mundane as public profile pictures. In fact, these days, more information can be gleaned by scraping publicly available data from Facebook than can be obtained through the API. The post-2014 policy has zero chance of any friend data being sold/abused/whatever, because apps simply don't have access to the data anymore.