There are multiple sources indicating that conservative sites work in concert to amplify, at best, specious content and at worst, complete misinformation.
Facebook selectively enforces discipline on these sites because:
1. Conservative information (Fox News, Charlie Kirk, Breitbart, etc.) is consistently shared more than other content
2. They don't want the optics of making it seem like they're censoring conservative voices because they're afraid of the blowback, so they're hiding behind the veil of "It's not our job"
3. They don't want to lose the ad spend running up to the election season nor do they want to lose the vanity metrics of DAU/MAU/etc because they're a publicly traded company
Zuck is a feckless coward, full stop. And while I don't know his personal political leanings, this non-policy certainly has the earmarks of Thiel and Joel Kaplan all over it.