Facebook has been banned in China since 2009 (Instagram since 2014), but ever since, there have been reports the company is trying to find its way back in. Earlier this year, Time documented a "charm campaign" by CEO Mark Zuckerberg, and today the New York Times reports it's working on tech that could be amenable to the country's censorship policies. It's not known if this will be implemented, or if China will allow access to the network again, but the code is apparently visible to employees.
This particular tool is different from existing blocking mechanisms because it would enable a third party to block popular stories or topics from popping up in user's feeds, without waiting for the government to make a specific request first. Facebook has openly maintained interest in operating in China, and accessing its large population would fit the company's stated goal of making the world more connected.
The real question is whether the creation and use of a tool like this would be worth it, and according to the article's author, Mike Isaac, fear of its use by a hostile US administration prompted some sources to speak out about it. A few years ago, rumors of unfettered access in an area of Shanghai arose before being quashed, so for now, things will remain as they have been, with Chinese users choosing between posting on Weibo or sneaking in via VPN.